Myxoid Stromal Changes Research Articles

Solitary fibrous tumor occurring at unusual sites: A clinico-pathological series of 31 cases with emphasis on its wide morphological spectrum

Solitary fibrous tumor (SFT) is a relatively rare mesenchymal fibroblastic tumor occurring most commonly in adults with no gender predilection. Although the pathological diagnosis of SFT is usually straightforward, some difficulties may occasionally arise mainly due to the wide morphological spectrum exhibited by this tumor. In the present paper we aimed to evaluate the unusual clinicopathological features in a series of 31 SFTs arising from parenchymal organs, superficial soft tissues and deep soft tissues. Our results emphasize that SFTs may occur anywhere, including unusual sites such as periosteum of the thoracic spine, mesorectal tissue, hepatic hilum, paravescial space, kidney and breast. Moreover, a wide morphological spectrum was observed in tumors included in our series. The most striking morphological features observed included: extensive lipomatous component, myxoid stromal changes, epithelioid cell component, metaplastic mature bone, neurofibroma-like, myxofibrosarcoma-like and pseudoalveolar-like areas. Additionally, multinucleated giant cells and sarcomatous dedifferentiation were also identified.Our paper emphasizes that SFT may occur in unusual anatomical locations and exhibits a wide morphological spectrum. Pathologists must be aware of these features to avoid confusion with other benign and malignant neoplasms that may show overlapping morphological features.

Morphological, immunohistochemical, and genetic analyses of epithelioid gastrointestinal stromal tumors

Epithelioid gastrointestinal stromal tumors (GISTs) are rare and may be confused with other tumors with epithelioid morphology. Therefore, herein, we collected 12 epithelioid GIST samples and summarized their morphological and immunohistochemical characteristics. Through genetic testing, we explored the correlation between morphology and gene mutations. The results showed that eight tumors showed focal or diffuse myxoid stromal changes with less cohesively arranged rhabdoid tumor cells; among these, five showed platelet-derived growth factor receptor alpha gene (PDGFRA) mutations. Signet ring cells with sclerosing stroma and receptor tyrosine kinase type III gene (KIT) mutations were present in two cases, which might be a KIT mutation-associated growth pattern in epithelioid GISTs. Succinate dehydrogenase gene (SDH) mutations were detected in three cases. Simultaneously, PDGFRA mutations were detected in two cases, and the Kirsten rat sarcoma viral oncogene homolog gene (KRAS) mutation was detected in another case. SDH-subunit B (SDHB) expression was partially weak and strongly diffuse in two cases with concurrent PDGFRA and SDHD mutations, respectively. The coexistence of PDGFRA and SDHD mutations may have affected SDHB expression. Altogether, we concluded that PDGFRA mutations may play an important role in co-mutant GIST pathogenesis.

An Outstanding Rapid Clinical Response to Olaparib in A Patient with gBRCA2m Fungating Breast Cancer: A Case Report

Background: Breast cancer is a heterogeneous, phenotypically complex disease made up of various biologic subgroups with unique behaviors and therapeutic responses. Noted that despite lack of a cure for metastatic breast cancer (MBC), there have been appreciable advancements in survival that have occurred at the same time as newer systemic treatments. BRCA1 or BRCA2 mutations cause homologous recombination deficient (HRD) cells, which are vulnerable to PARPi agent treatment. Case Report: This case report presents a 40 years old single female, known case of multiple co-morbidities who was diagnosed with Bilateral breast cancer in June 2022. She has a Positive family history of malignancy; mother died from endometrial cancer and aunt from paternal side has breast cancer. She underwent needle core biopsy from her Right breast mass, which revealed Invasive high-grade ductal carcinoma with metaplastic features (foci of keratinizing squamous differentiation, and myxoid stromal change). DCIS, of intermediate and high grades and a solid pattern, was noted, focally suspicious for lymphovascular invasion, Triple negative (ER negative (<1%), PR negative (<1%) and her-2 (+2) FISH negative (Her-2 Low), KI 67= 70%. Left breast mass Biopsy done on 12/9/2022 showed Invasive Lobular carcinoma, grade 3, ER negative, PR negative, Her-2 +1, KI 67=70%, BRCA2 POSITIVE & PDL1 CPS score 10%. Staging positron emission tomography scan done on 10 October 2022. She had a Large hypermetabolic fungating right breast mass infiltrating the chest wall, consistent with biopsy-proven malignancy. Additional smaller FDG-avid lesions noted in the right breast. Moreover, she had FDG-avid right axillary and right internal mammary nodal metastases. Mildly FDG-avid left breast mass, consistent with biopsy-proven malignancy. FDG-avid liver and pleural metastases. She was started on PARP inhibitor (Olaparib) on 20/9/2022 after which she had amazing fast clinical response leading to falling off the large fungating mass. Conclusion: The chance of developing breast and ovarian cancer is extremely elevated if one possesses BRAC 1 or BRCA 2 mutation. In this situation, PARP inhibitors, mutation-targeted therapy, has better outcomes in reducing the morbidity and mortality associated with metastatic breast cancer (Olaparib).

CIC-rearranged sarcoma with rhabdoid features: a clinicopathological analysis

Objective: To investigate the histopathologic, immunohistochemical, molecular genetic characteristics of CIC-rearranged sarcoma (CRS) with rhabdoid features. Methods: The clinical and pathologic data of two cases of CRS diagnosed between 2019 and 2021 at the Department of Pathology, Jiangsu Province Hospital were analyzed. Immunohistochemical study and fluorescence in situ hybridization (FISH) were performed. The relevant literature was reviewed. Results: Both patients were female, one was 58 years old, with tumor located in left thigh; the other was 43 years old, with tumor located in left pelvic cavity. Microscopically, both tumors were composed of small to medium-sized round, oval cells, arranged in nodules or sheets. The tumor cells showed irregular nuclear outline, coarse chromatin with prominent nucleoli and brisk mitotic activity. Both cases showed rhabdoid phenotype with myxoid stromal changes. Immunohistochemically, both cases were positive for CD99 and c-myc. High WT1 reactivity was seen in classic area, with low reactivity in rhabdoid area. There was no INI1 lost in both cases. Both were negative for NKX2.2 and NKX3.1. By FISH both cases demonstrated convincing break-apart signals of CIC gene. One patient died of disease after 1 month, and the other died of disease after 3 months. Conclusions: CRS is a small round cell undifferentiated sarcoma of the bone and soft tissue defined by molecular genetic characteristics, and may show atypical morphologic and immunophenotypic characteristics such as rhabdoid features. A correct understanding of its rare morphologic and immunophenotypic characteristics, combined with molecular pathologic detection, is conducive to correct diagnosis.

Recurrent YAP1::MAML2 fusions in “nodular necrotizing” variants of myxoinflammatory fibroblastic sarcoma: a comprehensive study of 7 cases

AbstractMyxoinflammatory fibroblastic sarcoma (MIFS) is a rare soft tissue tumor with a predilection for the distal extremities and a tendency for local recurrence. Morphologically, MIFS consists of spindle and bizarre epithelioid cells resembling virocytes embedded in a fibrous to myxoid stroma with an abundant inflammatory infiltrate. Importantly, the molecular landscape of MIFS is wide and includes: VGLL3 amplification, BRAF fusion/amplification and OGA/TGFBR3 rearrangements. In this study, we describe a variant of MIFS showing a frequent nodular configuration associated with necrosis and recurrent YAP1::MAML2 fusions. The cohort consisted of 7 patients (4 females and 3 males) ranging in age from 21 to 71 years (median: 47 years). Two tumors (28%) occurred in acral locations while the remaining cases were more widely distributed (thigh, n = 2; arm, n = 1; neck; n = 1; chest-wall, n = 1). Tumor size ranged from 10 to 38 mm (median: 20 mm). Histologically, lesions frequently presented as nodules with central areas of necrosis, and were predominantly composed of sheets of epithelioid cells with large vesicular nuclei and prominent nucleoli (Reed-Sternberg-like cells or virocytes). The stroma was mostly fibrous and showed a polymorphous inflammatory infiltrate. Myxoid stromal changes were focally seen in one case, and pseudolipoblasts were absent. The immunophenotype was nonspecific, with only pan-keratin (AE1-AE3) and cyclin D1 expression in a subset of cases. RNA-Sequencing detected YAP1::MAML2 fusions in 3/7 cases; aCGH showed no significant gene copy number variations in 4 tested cases, and FISH analysis showed no VGLL3 amplification in 1 tested case. Follow-up was available for 6 cases, ranging from 7 to 63 months (median: 42 months). Local recurrence and metastasis were not seen and one tumor showed spontaneous regression following initial biopsy. In conclusion, we describe a novel variant of MIFS with distinctive clinicopathological and molecular features for which we propose the term “nodular necrotizing” MIFS.

Recurrent KAT6B/A::KANSL1 Fusions Characterize a Potentially Aggressive Uterine Sarcoma Morphologically Overlapping With Low-grade Endometrial Stromal Sarcoma.

With the widespread application of next-generation sequencing, the genetic landscape of uterine mesenchymal neoplasms has been evolving rapidly to include several recently identified fusion genes. Although chromosomal rearrangements involving the 10q22 and 17q21.31 loci have been reported in occasional uterine leiomyomas decades ago, the corresponding KAT6B::KANSL1 fusion has been only recently identified in 2 uterine tumors diagnosed as leiomyoma and leiomyosarcoma. We herein describe 13 uterine stromal neoplasms carrying a KAT6B::KANSL1 (n=11) and KAT6A::KANSL1 (n=2) fusion. Patient ages ranged from 33 to 81 years (median, 49 y). Tumor size was 2.6 to 23.5 cm (median, 8.2 cm). Nine tumors were myometrium-centered, and 3 had an intracavitary component. Original diagnoses were mostly low-grade endometrial stromal sarcoma (LG-ESS; 10 cases) with atypical features (limited CD10 expression, sex cord-like features, pericytic vasculature, and frequent myxoid changes). Treatment was hysterectomy±bilateral salpingo-oophorectomy (10), myomectomy (1), and curettage (2). Five patients were disease-free at 6 to 34 months, 3 (27%) died of disease at 2 to 47 months, and 3 were alive with disease at 2, 17, and 17 years. Histologically, most tumors showed variable overlap with LG-ESS, but they were generally well-circumscribed lacking the extensive permeative and angioinvasive growth typical of LG-ESS. They were composed of monotonous medium-sized oval and spindle cells arranged into diffuse sheets with prominent spiral-type arterioles and frequent pericytoma-like vascular pattern. Variable myxoid stromal changes were frequent. Mitotic activity ranged from 1 to >20 in 10 HPFs. Immunohistochemistry showed variable expression of CD10 (12/13), estrogen receptor (8/11), progesterone receptor (8/11), smooth muscle actin (9/11), desmin (4/12), h-caldesmon (2/10), calretinin (3/8), inhibin (1/7), WT1 (4/7), cyclin D1 (5/11; diffuse in only 1 case), and pankeratin (5/10). This series characterizes a KAT6B/A::KANSL1 fusion-positive uterine stromal neoplasm within the morphologic spectrum of LG-ESS but with atypical features. The relationship of these neoplasms to genuine LG-ESS remains unclear. This molecular subtype of uterine endometrial stromal sarcoma has the potential for an unfavorable clinical course despite the absence of widely invasive growth; nevertheless, analysis of more cases is necessary to delineate the phenotypic spectrum and biological potential of this tumor.

Superficial CD34-positive fibroblastic tumor and PRDM10-rearranged soft tissue tumor are overlapping entities: a comprehensive study of 20 cases.

Superficial CD34-positive fibroblastic tumor (SCD34FT) and PRDM10-rearranged soft tissue tumor (PRDM10-STT) are rare mesenchymal tumors. These lesions have clinicopathological similarities, but their relationship remains controversial. This study aimed to characterise a series of cases of SCD34FT and PRDM10-STT. Ten lesions each of SCD34FT and PRDM10-STT were studied using immunohistochemistry, array-comparative genomic hybridisation (aCGH), RNA sequencing and exome sequencing. Tumors mainly occurred in young adults, were generally small (<5cm) and arose predominantly in the superficial soft tissues of the lower extremities. Follow-up data were available in 15 cases (SCD34FT, n=7, median 16months; PRDM10-STT, n=8, median 14months), local recurrences occurred in four cases (SCD34FT, two of 10; PRDM10-STT, two of 10), while no distant spread was documented. Morphologically, tumors were relatively well-circumscribed and composed of sheets and fascicles of spindle and pleomorphic cells showing low mitotic activity (<1/mm²) without necrosis. Other findings included: granular cell change, lipoblast-like cells, ectatic blood vessels with fibrinous material, myxoid stromal changes, metaplastic bone and increased mitotic activity (>1/mm²). All tumors diffusely expressed CD34, while pan-keratin and desmin were commonly seen focally. SynCAM3 was diffusely expressed in 12 cases (SCD34FT, n=5; PRDM10-STT, n=7), independently of fusion status. aCGH profiles were 'flat' (PRDM10-STT, n=4; SCD34FT, n=2) and exome sequencing showed no recurrent pathogenic mutations (PRDM10-STT, n=2; SCD34FT, n=4). Overall, the only morphological features seen exclusively in PRDM10-STT were myxoid stromal changes (three of 10) and metaplastic bone (two of 10). We expand the current knowledge on PRDM10-STT and SCD34FT and provide additional evidence for considering them as overlapping entities.

Presence of myxoid stromal change and fibrotic focus in pathological examination are prognostic factors of triple-negative breast cancer: Results from a retrospective single-center study.

Stromal reaction is an important prognostic factor in several cancers, and the presence of myxoid change was assessed as a poor prognostic factor in colorectal cancer. However, the prognostic significance of myxoid change in triple-negative breast cancer (TNBC) remains unknown. This study aimed to determine the prognostic significance of myxoid change and fibrotic focus (FF), which is a fibrotic area within the tumor and considered a poor prognostic indicator in patients with TNBC. We enrolled 62 patients with TNBC and reviewed the surgically resected specimens to evaluate myxoid change and FF in the tumor using previously outlined criteria. We evaluated tumor-infiltrating lymphocytes (TILs) using hematoxylin and eosin slides. Overall survival (OS) and relapse-free survival (RFS) were compared based on the presence of myxoid change and/or FF, and the risk factors for RFS were analyzed. Myxoid change and FF were observed in 25.8% and 33.9% of specimens, respectively. Based on stromal lymphocyte infiltration, 19 patients (30.6%) had high TILs, while the remaining 43 patients (69.4%) had low/intermediate TILs. Presence of myxoid change was significantly correlated with poor OS and RFS (p = 0.040 and 0.031, respectively). FF was also significantly correlated with poor OS and RFS (p = 0.012 and 0.028, respectively). The combination of myxoid change and FF was an independent and poor prognostic factor according to the multivariate analysis (HR 11.61; 95% CI 1.027-131.2; p = 0.048). Presence of myxoid change and FF were significantly associated with low/intermediate TILs in the stroma (p = 0.013). Histopathological assessment of myxoid change and FF in TNBC may be a useful, practical, and easily assessable method for predicting prognosis in patients with TNBC, which should be confirmed in larger prospective studies. Diagnostic criteria for the establishment of myxoid change and FF in TNBC must be established, and their underlying molecular events must be clarified.

Genomic profiling of BCOR-rearranged uterine sarcomas reveals novel gene fusion partners, frequent CDK4 amplification and CDKN2A loss

ObjectiveGenomic alterations of BCOR via ZC3H7B-BCOR fusion or BCOR internal tandem duplication (ITD) define a subset of endometrial stromal sarcoma (ESS). The goals of this study were to: 1) determine the molecular landscape of BCOR-rearranged ESS, 2) to identify novel BCOR fusion gene partners in ESS and their associated clinicopathological characteristics, and 3) to potentially unravel targetable genomic alterations in BCOR-mutated ESS. MethodsA retrospective database search of a CLIA-certified molecular laboratory was performed for uterine sarcomas that contained BCOR rearrangements or BCOR ITD. The cases were previously assayed by comprehensive genomic profiling via both DNA- and RNA-based targeted next generation sequencing during the course of clinical care. Clinicopathological and genomic data was centrally re-reviewed. ResultsWe identify largest cohort of BCOR-rearranged ESS to date (n = 40), which included 31 cases with canonical ZC3H7B-BCOR fusion as well as 8 cases with novel BCOR gene rearrangement partners, such as BCOR-L3MBTL2, EP300-BCOR, BCOR-NUTM2G, BCOR-RALGPS1, BCOR-MAP7D2, RGAG1-BCOR, ING3-BCOR, BCOR-NUGGC, KMT2D-BCOR, CREBBP-BCOR and 1 case with BCOR internal rearrangement. Re-review of cases with novel rearrangements demonstrated sarcomas with spindle, epithelioid or small round cell components and frequent myxoid stromal change. Comprehensive genomic profiling revealed high frequency of CDK4 and MDM2 amplification in 38% and 45% of BCOR-rearranged cases, respectively, and homozygous deletion of CDKN2A, which encodes an inhibitor of CDK4 in 28% of cases. Notably, CDK4 and MDM2 amplification was absent in all cases from 15 different ESS cases harboring BCOR ITD. ConclusionsAlterations of CDK4 pathway members, for which targeted therapy is clinically available (i.e. palbociclib), via CDK4 amplification or CDKN2A loss, contributes to the pathogenesis of BCOR-rearranged uterine sarcomas, which may have therapeutic implications.

The clinicopathological spectrum of pseudomyogenic hemangioendothelioma: report of an additional series with review of the literature.

We present here our experience with 24 cases of pseudomyogenic hemangioendothelioma (PMHE) to further delineate its clinicopathological spectrum. There were 18 males and 6 females with a median age of 28years (range 10~64years). Most patients presented with erythematous nodules or papules, with or without pain. The majority (63%) occurred in the lower extremities, whereas a minority involved the trunk (25%), upper extremities (8%), and head and neck (4%). Six cases (25%) had a primary bone origin. With physical and radiological examinations, 16 cases (67%) manifested as multifocal disease, involving multiple tissue planes or different bones within the anatomic region. Six cases (25%) involved skin, soft tissue, and bone simultaneously. Histologically, all cases showed features consistent with a PMHE characterized by loose fascicles or sheets of plump spindled to epithelioid cells harboring brightly eosinophilic cytoplasm and vesicular nuclei. In addition, five cases (21%) contained a prominent myxoid matrix, and one case displayed perineural and intravascular invasion. The follow-up information available in 18 patients revealed local recurrence in 4 patients (22%) and persistent disease in 8 patients (44%), respectively. One patient developed bilateral pulmonary metastases which showed significant remission after systemic chemotherapy. None of the patients died of the disease. As the clinical appearance of PMHE can be deceptive, a radiological examination is essential in identifying an insidious multifocal disease. Although PMHE has a predilection for the distal extremities of young males, this rare tumor type could also occur in unusual sites and affect middle-aged adults of both genders. The striking myoid appearance in association with myxoid stromal change may represent a potential diagnostic pitfall. Biologically, PMHE has an indolent clinical behavior, albeit metastatic disease may occur in rare instance.

Clinicopathologic and molecular characterizations of Sertoli cell tumor, not otherwise specified of the testis

Objective: To investigate the histomorpholgic spectrum, immunophenotypic, and molecular genetic features of Sertoli cell tumor, not otherwise specified (SCT, NOS) of the testis. Methods: Seven cases of SCT, NOS of the testis were analyzed(4 from Peking University Third Hospital and 3 from Zhejiang Provincial People's Hospital) between 2008 and 2017. The histopathologic features were examined based on HE staining, and EnVision method was used for immunohistochemistry staining of calretinin, inhibin, β-catenin, cyclinD1, CD10, CKpan, neuroendocrine markers, WT1, Melan A, vimentin, SALL4, GATA3, PAX8, and S-100 protein. Mutational analysis of exon 3 of the CTNNB1 gene by polymerase chain reaction (PCR)-amplified sequences and direct sequencing was performed. Results: Patients ages ranged from 22 to 65 years (mean 43 years). The clinical manifestation in all was a slowly enlarging, painless testicular mass.The maximum diameter of the tumor ranged from 1.5 cm to 3.0 cm (mean 2.1 cm). Sectioning usually disclosed a tan-gray to white mass with vague lobular cut-surface. Microscopically, the tumors were well circumscribed and non-encapsulated; the tumor cells were rearranged in multiple growth patterns from diffuse solid sheets to trabeculae and cords, ribbon and solid or hollow tubules setting in variable amount of acellular fibrous stroma. Two cases showed acellular collagenous stroma constituted >50% of the tumor confirming to the diagnosis of sclerosing SCT. One case demonstrated a prominent myxoid stromal change. The tumor cells typically had moderate amounts of pale to lightly eosinophilic cytoplasm, 2 tumors had variable cells with abundant lipid-rich cytoplasm, and 1 other tumor showed scattered aggregates of multinucleated tumor cells. The tumor cells were bland-appearing without any evidence of atypia, mitoses were noted in 2 tumors (both were 1/50 HPF), but necrosis was absent. Immunohistochemical staining results as follows: vimentin (diffuse, 7/7), CD10 (diffuse membrane, 7/7); diffuse β-catenin nuclear and cytoplasm staining in 5 of 7 cases, and all the 5 cases showed diffuse cyclin D1 nuclear staining, β-catenin membrane staining in 2 of 7 cases, CKpan (5/7, focal or diffuse), calretinin (focal, 5/6), inhibin (focal, 3/7), synaptophysin (focal, 2/6), CD56 (focal or diffuse, 4/5), WT1 (diffuse nuclear, 4/5), and S-100 protein (diffuse, 3/7), and chromogranin A, Melan A, PAX8, GATA3 and SALL4 all were negative. Molecular genetic studies of PCR and direct sequencing showed CTNNB1 mutations in 4 of 7 (4/7) cases, 4 of the four mutation-carrying cases showed diffuse β-catenin nuclear and cytoplasm immunoreactivity and diffuse cyclin D1 nuclear immunoreactivity in the tumor cells. Conclusions: SCT, NOS of the testis typically shows significant heterogeneities in both morphology and immunohistochemistry, thus causing differential diagnostic confusions. Molecular analyses showed mutations of exon 3 of CTNNB1 in more than half of these tumors, and nuclear accumulation of β-catenin and over expression of cyclin D1 can be useful for the differential diagnosis of SCT, NOS.

Sarcomas With CIC-rearrangements Are a Distinct Pathologic Entity With Aggressive Outcome: A Clinicopathologic and Molecular Study of 115 Cases.

CIC-DUX4 gene fusion, resulting from either a t(4;19) or t(10;19) translocation, is the most common genetic abnormality detected in EWSR1-negative small blue round cell tumors. Following their discovery it was debated if these tumors should be classified as variants of Ewing sarcoma (ie, atypical Ewing sarcoma) or as a stand-alone pathologic entity. As such the WHO classification temporarily grouped the CIC-rearranged tumors under undifferentiated sarcomas with round cell phenotype, until further clinical evidence was available. However, most studies reported so far include small series with limited follow-up information, which preclude a more definitive assessment. The present work investigates the clinicopathologic features of a large cohort of sarcomas with CIC gene rearrangement, to define their clinical presentation, morphologic spectrum, and outcome. Our study further examines the overall survival of the CIC-positive cohort compared with a control group of EWSR1-rearranged Ewing sarcoma matched for age and stage. The study cohort included 115 patients, with a mean age of 32 years and a slight male predominance. Most tumors occurred in the soft tissue (86%), predominantly deep-seated and equally divided among trunk and extremity, followed by visceral locations (12%) and rarely in the bone (3%). Microscopically, most tumors showed round to ovoid cytomorphology but half of the cases showed also focal areas of spindling and epithelioid/rhabdoid phenotype, with frequent myxoid stromal changes. Variable CD99 reactivity was seen in 84% cases, with a diffuse pattern only in 23% of cases, whereas nuclear WT1 was seen in 92%. A CIC-DUX4 fusion was detected in 57% of cases, with either DUX4 on 4q35 (35%) or on 10q26 in 25 (22%) cases. No FOXO4 gene rearrangements were present in 39 cases tested. Clinical follow-up was available in 57 patients, with a 5-year survival of 43%, which was significantly lower than the 77% 5-year survival in the control Ewing sarcoma group (P=0.002). Our findings show that CIC-DUX4 sarcomas occur most commonly in young adults within the somatic soft tissues, having a wide spectrum of morphology including round, epithelioid and spindle cells, and associated with an aggressive clinical course, with an inferior overall survival compared with Ewing sarcoma. The results support the classification of CIC-rearranged tumors as an independent molecular and clinical subset of small blue round cell tumors distinct from Ewing sarcoma.

Giant nodular pseudoangiomatous stromal hyperplasia of the breast with fbroadenomatoid myxoid changes: a potential pitfall in the differential diagnosis of phyllodes tumor

ABSTRACT A 21-year old woman presented with a 17-cm left breast mass. Physical examination and ultrasound revealed the mass to be well-circumscribed, homogeneous and freely mobile, suggestive of giant fibroadenoma or phyllodes tumor. The mass was surgically excised and initially interpreted as benign phyllodes tumor. Subsequent slide review established the diagnosis of nodular pseudoangiomatous stromal hyperplasia (PASH) associated with fibroadenomatoid areas and myxoid stromal changes. This case illustrates the difficulty encountered in recognizing nodular PASH. A thorough discussion of the histopathologic differential diagnosis of nodular PASH is provided.

Extensively Myxoid and Hyalinized Sinonasal Capillary Hemangiomas: A Clinicopathologic Study of 16 Cases of a Distinctive and Potentially Confusing Hemangioma Variant.

Capillary hemangiomas, the most common vascular tumors of the sinonasal region, are benign endothelial neoplasms, typically growing in an easily recognized lobular pattern. Some sinonasal capillary hemangiomas may show atypical features, such as high cellularity or mitotic activity, and represent more challenging diagnoses. Over the past several years we have seen in consultation a number of examples of sinonasal capillary hemangiomas displaying very striking stromal myxoid change and hyalinization, features that have received scant attention in the past. Available slides from 16 sinonasal capillary hemangiomas previously coded as showing such changes were retrieved from our archives. Submitting diagnoses included "query angiofibroma, rule out malignancy" (N=4), "vascular polyp, rule out malignancy" (N=3), "query malignant vascular tumor" (N=4), "sinonasal hemangiopericytoma" (N=1), and "benign vascular tumor" (N=1). Available radiographic studies often showed worrisome features. Grossly, the tumors ranged from 1.1 to 6.0 cm and appeared as ulcerated, vascular-appearing polyps. Microscopically, the tumors showed striking stromal myxoid change and/or hyalinization, which largely obscured the underlying lobular capillary arrangement. Within this myxohyaline matrix, a florid capillary proliferation was present, frequently with nonatypical mitotic activity. In some instances a branching, "hemangiopericytoma-like" vascular pattern was present in areas. The overall cellularity was low to moderate, and endothelial atypia or hyperchromatism was absent. Ulceration and thrombosis were frequently present. Immunostains to CD31, CD34, and SMA highlighted areas of lobular growth pattern inapparent on the routinely stained slides. Four tested cases were negative for androgen receptors and β-catenin. Follow-up from 12 patients revealed no local recurrences or metastases. Awareness of that sinonasal capillary hemangioma may show these unusual stromal changes, and the use of ancillary immunohistochemistry to highlight its lobular growth pattern should allow its confident distinction from more aggressive endothelial tumors (eg, angiosarcoma) and from nonendothelial tumors, including nasopharyngeal angiofibroma, solitary fibrous tumor, and sinonasal hemangiopericytoma-like tumor.

A Case of Myxoid Dermatofibrosarcoma Protuberans

Dermatofibrosarcoma protuberans (DFSP) is a slow-growing dermal spindle cell tumor. Its rare myxoid variant is characterized by extensive myxoid degeneration. We report a case of myxoid DFSP of the lower abdomen in a 35-year-old man. Histopathologically, the tumor consisted of spindle-shaped cells that were strongly positive for CD34 with a typical storiform pattern and myxoid stromal changes.

A case of ‘fat-free’ pleomorphic lipoma occurring in the upper back and axilla simultaneously

Pleomorphic lipoma is a rare neoplasm that predominantly occurs in the dermis or subcutis of the posterior neck, upper back, and shoulders. Although pleomorphic lipoma is a benign tumor, it may contain atypical cells. As a variant of spindle cell lipoma, pleomorphic lipoma clinically presents as a slow-growing and well-circumscribed subcutaneous mass. Rarely, some patients have multiple lesions. Histologically, pleomorphic lipoma is composed of mature fat, bland spindle-shaped mesenchymal cells, and coarse ‘rope-like’ collagen bands. In addition, lipoma contains multinucleated floret-like giant cells. Although spindle cell lipoma/pleomorphic lipoma with little fat was seen in the original series described by Enzinger and Harvey, cases with little to no fat remain diagnostically challenging. Herein, we report a case of ‘fat-free’ pleomorphic lipoma occurring in the upper back and axilla simultaneously. Although the lipoma was typically composed of bland spindle-shaped cells, rope-like collagen, scattered floret-like giant cells, and striking stromal myxoid change in the background, mature fat was absent. Immunohistochemical analyses showed positive staining for CD34, vimentin, and Bcl-2, and negative staining for S100, confirming the diagnosis of pleomorphic lipoma.

Desmoplastic Fibroblastoma Presenting as a Parotid Tumour: A Case Report and Review of the Literature

Desmoplastic fibroblastomas (DFs) are rare fibrous soft tissue tumours that usually arise in subcutaneous tissue or skeletal muscle in a variety of anatomical sites. These lesions most frequently present as painless, slow-growing mobile masses. A case of DF is described in a 47-year-old man who presented with a painless right parotid mass of 2months duration. At surgery, the lesion was attached to the tail of the right parotid gland. Histopathological examination demonstrated a fibrous lesion comprising spindled and stellate shaped fibroblasts with focal myxoid stromal change. The features were consistent with a DF. This report documents a rare parotid lesion which may mimic other more common parotid gland neoplasms.

Myxoid Dermatofibrosarcoma Protuberans of the vulva with myoid nodules: Clinicopathologic and Immunohistochemical study of a case

Dermatofibrosarcoma protuberans is a slow growing dermal spindle cell tumor seldom seen in the vulva and its myxoid variant, a rare type of dermatofibrosarcoma protuberans is characterised by extensive myxoid degeneration. We present the case of a 62 year old woman with an enlarging vulval swelling. Mass was excised surgically. Histopathologically the tumor consisted of uniform spindle-shaped cells showing strong positivity with CD34. In addition to the typical storiform pattern and lace like infiltration, prominent myxoid stromal changes were seen. Herein we report an interesting case of myxoid dermatofibrosarcoma protuberans, uncommonly reported in the dermatopathology literature.

Multifocal Uterine Myxoid Change

Stromal myxoid change is a rare feature of non-neoplastic disease of the uterus. "Myometrial myxoidosis" with secondary myometrial hypertrophy was reported in 2 patients with systemic lupus erythematosus. Uterine myxoid stromal change was also described as an unusual pseudoneoplastic condition of uncertain etiology in 3 patients, one of whom had neurofibromatosis type 1 (NF1; von Recklinghausen disease). We have now identified multifocal uterine myxoid change in the hysterectomy specimen of another patient with NF1; we describe the findings in both patients and review the relevant literature. The myometrium and cervical stroma in both NF1 patients contained tracts and nodules of hypocellular myxoid stromal material composed of bland spindle-shaped cells and interspersed small blood vessels. The myxoid stromal material was strongly and diffusely immunopositive for CD34 and CD10 but did not label for desmin, smooth muscle actin, h-caldesmon, neurofilament protein, S100, or epithelial membrane antigen. The myxoid material in the NF1 patients was better demarcated than in the 2 reported cases of myometrial myxoidosis in systemic lupus erythematosus, and more widely distributed, extensively involving the cervix and the myometrium. The occurrence of this rare, distinctive pattern of multifocal uterine myxoid change in 2 patients with NF1 seems unlikely to represent simply a chance association. The identification of multifocal uterine myxoid change in non-neoplastic myometrium or cervical stroma should raise the possibility of underlying NF1.

Palisaded Encapsulated Neuroma: An Entity to Consider in the Differential Diagnosis of the Eyelid Nodule. A Case Report

A 58-year-old female presented to her ophthalmologist with a firm 5 mm × 5 mm painless nodule on her right eyelid that had been present for 4 years. The nodule was well encapsulated and was composed of spindled cells. The central portion of the tumor contained a neuroid cell population with tapered ends. The periphery of the neuroid cell population exhibited a palisading pattern. Myxoid stromal changes could be appreciated between the neuroid cell population and the capsule. Routine hematoxylin-eosin staining and S100, epithelial membrane antigen, and neurofilament were used to diagnose the nodule as palisaded and encapsulated neuroma, a benign peripheral nerve sheath tumor derived from Schwann cells.