Spindle Cell Tumor Research Articles

Natural history and treatment efficacy in an ambispective case series of NTRK-rearranged mesenchymal tumors

Apart for infantile fibrosarcoma (IFS), very little is known about NTRK-rearranged mesenchymal tumors (NMTs). The objective of this study is to describe the distribution, characteristics, natural history, and prognosis of NMT. This study was carried out as a translational research program, retrospectively from a cohort of 500 soft tissue sarcoma (STS; excluding IFS) and prospectively both in routine practice and from the RNASARC molecular screening program (N= 188; NCT03375437). Using RNA-sequencing, NTRK fusion was detected in 16 patient tumors diagnosed as STS: 8 samples of sarcoma with simple genomics (4 NTRK-rearranged spindle cell neoplasm, 3 ALK/ROS wild-type inflammatory myofibroblastic tumor, and 1 quadruple Wild-type gastrointestinal stromal tumor) and 8 samples of sarcomas with complex genomics (dedifferentiated liposarcoma, intimal sarcoma, leiomyosarcoma, undifferentiated pleomorphic sarcoma, high-grade uterine sarcoma, malignant peripheral nerve sheath tumor). Among the eight patients with simple genomics, four were treated with tyrosine receptor kinase inhibitor (TRKi) at different stages of the disease and all benefited from the treatment, including one complete response. Among the eight other patients, six evolved with metastatic spreading and the median metastatic survival was 21.9 months, as classically reported in these tumor types. Two of them received a first-generation TRKi without objective response. Our study confirms low frequency and histotype diversity of NTRK fusion in STS. While the activity of TRKi in simple genomics NMT is confirmed, our clinical data encourage subsequent studies focusing on the biological relevance of NTRK fusions in sarcomas with complex genomics together with the efficacy of TRKi in this population.

An incidental discovery of a gastric follicular dendritic cell sarcoma: A rare case report and a literature review

Introduction: Follicular dendritic cell sarcomas (FDCS) are rare tumours, typically seen in lymph nodes. However, in about one third of the reported cases, a FDCS presents as an extranodal mass. Involvement of the gastrointestinal tract is rare, and the stomach is even rarer with only four cases described to date. The aim of this study was to review clinical characteristics, pathologic features, emphasize on differential diagnosis and discuss therapeutic modalities and prognosis of this rare entity.Case presentation: We report on a 36-year-old female patient with no past medical history, an incidentally discovered FDCS located in the stomach with the presence of lymph node metastasis at the time of diagnosis. The diagnosis of a FDCS was made on morphological and immunohistochemical findings where tumor cells expressed CD21 and CD23. The tumor was resected by gastrectomy with extended para-aortic lymphadenectomy, with uneventful postoperative course.Conclusions: Due to its rarity, FDCS is rarely included in the differential diagnosis of gastrointestinal spindle cell tumors. Complete surgical resection is the current gold standard of treatment.

VIM::KMT2A-rearranged sarcomas: A report of two new cases confirming an entity with distinct histologic features.

The recently described KMT2A-rearranged sarcomas are rare emerging entities where the KMT2A gene fuses with YAP1 and, less commonly, VIM, resulting in two distinct morphologies. Unlike the sclerosing epithelioid fibrosarcoma-like features that characterize tumors with KMT2A::YAP1 fusions, VIM::KMT2A-rearranged sarcomas are more uniformly cellular and lack the extensively sclerotic background seen in the former. Most tumors behave aggressively with metastases on presentation. Here, we describe the clinicopathologic and molecular findings in two additional cases of VIM::KMT2A rearranged sarcomas that arose in the deep soft tissues of adult males. Both tumors were composed of hypercellular fascicles of uniform spindle cells with pale eosinophilic cytoplasm and ovoid nuclei. The stroma had scant delicate collagen with occasional thin-walled ectatic blood vessels and perivascular hyalinization. Immunohistochemical studies showed an unspecific staining pattern with diffuse positivity for CD99 and BCL2 and variable staining for S100 protein. RNA-sequencing detected the presence of VIM::KMT2A gene fusion involving VIM exon 4 and KMT2A exon 2 in both cases. Sarcomas with VIM::KMT2A gene fusions seem to have sufficient morphologic features to warrant distinction from KMT2A-rearranged sarcomas with YAP1 partner. Without the benefit of molecular testing, these tumors pose a diagnostic challenge due to their lack of specific immunohistochemical profile and great morphologic overlap with other monomorphic spindle cell neoplasms.

Epithelioid and spindle rhabdomyosarcoma with TFCP2 rearrangement in abdominal wall: a distinctive entity with poor prognosis

BackgroundEpithelioid and spindle rhabdomyosarcoma (ES-RMS) with TFCP2 rearrangement is a recently discovered rare variant of rhabdomyosarcoma composed of epithelioid and spindle cells, because it shows extraordinarily adverse prognosis and is easily misdiagnosed as other epithelioid or spindle cell tumors.MethodsA rare case of ES-RMS with TFCP2 rearrangement was presented and English literatures in Pubmed online up to 01 July 2022 were gathered by two authors for a systematic review according to the inclusion and exclusion criteria.Case presentation/resultsWe report a case of ES-RMS in an early 30s-years-old female, the neoplastic cells are remarkably immunoreactive with CK(AE1/AE3), and partially with ALK protein. Unexpectedly, the tumor shows TFCP2 rearrangement with coexistence of increased copy numbers of EWSR1 and ROS1 gene and MET gene mutation. Besides, Next-generation sequencing for genetic mutational profiling revealed frequent MET exon14 mutations in chromosome 7, most of which are C > T nonsynonymous SNV, and exon42 of ROS1 in chromosome 6 showed frequent G > T mutation up to 57.54%. In addition, neither MyoD1 mutation nor gene fusions were detected. Moreover, the patient shows high tumor mutational burden (TMB) up to 14.11 counts/Mb. Finally, as many cases of ES-RMS including our case had local progression or metastasis, we find, similar to epithelioid rhabdomyosarcoma (median survival time is 10 month), ES-RMS shows a more aggressive behavior and adverse prognosis (median survival time is 17 month) than spindle cell/sclerosing rhabdomyosarcoma (median survival time is 65 month) according previous studies.ConclusionsES-RMS with TFCP2 rearrangement is a rare malignant tumor and easily confused with other epithelioid or spindle cell tumors, it may harbor additional gene alteration in addition to TFCP2 rearrangement, such as MET mutation, increased copy numbers of EWSR1 and ROS1 gene, high TMB. Most importantly, it may show very poor outcome with extensive metastasis.

Radiation-induced fibrosarcoma after breast-conserving therapy for breast cancer: a case report and literature review

BackgroundRadiation-induced sarcoma (RIS) has a 10-year incidence of 0.2–0.27% and a poor prognosis, although the radiation should need for breast-conserving surgery. In particular, radiation-induced fibrosarcoma has been rarer, and its incidence is 2.6–3.7% of RIS.Case presentationA 43-year-old woman with pT1N1M0 breast cancer underwent breast-conserving surgery, chemotherapy, radiation therapy 8 years ago, and continued hormonal therapy. She complained of a hard unprotruded mass palpated in her right upper outer quadrant of breast. Although we suspected local recurrence, core needle biopsy revealed atypical spindled tumor cells without mammary or epithelial markers. A diagnosis of fibrosarcoma was made via tumorectomy. She underwent additional enlarged surgery.ConclusionsWe report a rare case of fibrosarcoma in breast after breast-conserving surgery and radiation therapy. Fibrosarcoma after radiation therapy for breast cancer has been reported in 30 cases, including the present case. The dead and alive cases were not significantly different in terms of age, primary breast cancer, radiation dose, and following months. Patients with breast masses after radiation therapy should be suspected local recurrence and RIS.

Myoid Gonadal Stromal Tumor: A new Case Report with a Review of the Literature.

The myoid gonadal stromal tumor is a very rare testicular spindle cell tumor. Few cases have been reported in the literature from 1977 to 2022. It was an emerging entity in the fourth edition of the WHO Classification of Tumors of the Urinary System and Male Genital Organs and has been instated as a full benign entity in the new edition of 2022. We report herein an additional case of a myoid gonadal stromal tumor. It was a 27-year-old man who presented with an asymptomatic mass in his left testicle for 2 months. The mass was confirmed by ultrasound as a 3 cm solid well-circumscribed lesion for which orchiectomy has been performed. The histological analysis of the specimen and the immunohistochemistry staining was consistent with a myoid gonadal stromal tumor. The characteristics of this tumor are summarized in well-circumscribed, nonencapsulated masses of uniform spindle cells, and immunohistochemically, tumor cells coexpress SMA and S-100 protein. The benign behavior of this tumor is demonstrated by our results and those presented in the previous cases reported in the literature.

Atypical spindle cell/pleomorphic lipomatous tumour (ASPLT): A report of three FNA cases and comparison with spindle cell/pleomorphic lipoma cytopathology.

Atypical spindle cell/pleomorphic lipomatous tumour (ASPLT) is an infrequently appreciated benign lipomatous neoplasm newly accepted into the most recent WHO classification of soft tissue tumours. Our cytopathology files were searched for examples of ASPLT and spindle cell/pleomorphic lipoma (SCPL) having histopathological verification. Conventional fine needle aspiration (FNA) biopsy smears were performed using standard techniques. Eleven patients including three cases of ASPLT and eight of SCPL (M:F=4.5:1; age range: 39-97 years, mean age=60 years) met the inclusion criteria. FNA biopsy sites included extremity (5, 45%), trunk (3, 27%), and head/neck (3, 27%). All aspirates were from primary neoplasms. FNA diagnoses of ASPLT cases were spindle cell lipomatous neoplasm, fibrotic low-grade SC neoplasm, and myxoid lipomatous neoplasm. Eight SCPL cases were diagnosed as spindle cell neoplasm (3), spindle cell lipoma (SCL) (1), pleomorphic lipoma (1), suspicious for SCL (1), benign adipose tissue (1), and benign spindle cells and connective tissue (1). Ancillary testing in two ASPLT cases showed positive CD34 and negative MDM2 immunostain in one, and negative FISH results for MDM2 and DDIT3 in another. ASPLT is a novel lipomatous neoplasm simulating primarily SCPL and atypical lipoma/well-differentiated liposarcoma. Diligent cytomorphological observation, clinical information, and ancillary testing may allow for its specific recognition using FNA biopsy.

Top 10 Significant Spindled Head and Neck Lesions to Scrutinze.

Spindled lesions are a challenging area in head and neck pathology. This is particularly true in the sinonasal tract, where several uncommon entities with both unique and overlapping morphologic, immunophenotypic, and/or molecular features can occur. Review. The clinicopathologic characteristics of biphenotypic sinonasal sarcoma and nine important differential diagnostic considerations with one or more overlapping feature are summarized to establish a practical framework for approaching spindled lesions of the sinonasal tract. Morphologic evaluation is central to the work up of sinonasal spindle cell lesions-in particular, cellular morphology, tumor architecture and growth pattern, and the presence of admixed epithelial elements - however, focused immunohistochemical analysis of neural, myogenic, rhabdomyoblastic, epithelial, and/or melanocytic marker expression and/or ancillary tests for tumor-specific molecular alterations may be necessary for definitive diagnosis.

Top 10 Differential Diagnoses for Desmoplastic Melanoma.

Desmoplastic melanoma is a rare subtype of melanoma mainly appearing on sun-exposed skin. Clinically, it is many times non-pigmented and therefore the diagnosis is often not suspected. Review article. In this paper we review the main histopathological, immunohistochemical, and molecular features of desmoplastic melanoma, as well as the top 10 morphologic differential diagnoses which should be considered in most cases. The histopathological pattern can be many times deceptive, mimicking a scar, a fibrous reaction, a fibrohistiocytic tumor such as a dermatofibroma, a vascular tumor such as angiosarcoma, a smooth muscle tumor such as leiomyosarcoma, or a neural tumor. Although an overlying atypical junctional melanocytic proliferation may be seen in most cases, it is absent in a significant percentage (up to 30%) of cases, making the diagnosis even more difficult in those instances. The range of diagnostic pitfalls is wide, which may present disastrous prognostic consequences. Desmoplastic melanoma is often a difficult diagnosis to make, as it frequently shows nonspecific clinical findings and overlapping histologic features with many other tumors. However, the potential clinical and prognostic consequences of misdiagnosis as another entity are great. Therefore, this diagnosis must always be kept in mind when encountering spindle cell tumors affecting the head and neck area.

Breast metastasis in high-grade endometrial stromal sarcoma (HG-ESS) with BCOR rearrangement: a case report of a novel metastatic site

BackgroundThe ZC3H7B-BCOR fusion gene has recently been described in tumours with kinship to so-called high grade endometrial stromal sarcoma (HG-ESS). This subset of tumour behaves similarly to YWHAE-NUTM2A/B HG-ESS, however, they are both morphologically and immunophenotypically distinct neoplasms. The identified rearrangements in the BCOR gene have been accepted as both the driver and requisite feature in creating a novel sub-entity within the category of HG-ESS.Preliminary investigations into BCOR HG-ESS have shown similar outcomes to YWHAE-NUTM2A/B HG-ESS, with patients typically presenting with high stage disease. Clinical recurrences and metastases to lymph nodes, sacrum/bone, pelvis/peritoneum, lung, bowel and skin have been identified. In this report, we describe a case of BCOR HG-ESS, that is deeply myoinvasive and widely metastatic. Metastatic deposits include a mass in the breast discovered on self-examination; a metastatic site that has yet to be reported in the literature.Case presentationA 59-year-old female underwent biopsy for post-menopausal bleeding, yielding a diagnosis of “low-grade spindle cell neoplasm with myxoid stroma and endometrial glands”, favouring endometrial stromal sarcoma (ESS). She was then referred for total hysterectomy and bilateral salpingo-oophorectomy. The resected uterine neoplasm was both intracavitary and deeply myoinvasive with morphology consistent with that of the biopsy specimen. Characteristic immunohistochemistry (IHC) was noted, and fluorescence in situ hybridization confirmed BCOR rearrangement, supporting a diagnosis of BCOR HG-ESS. A few months postoperatively, the patient underwent needle core biopsy of the breast which revealed metastatic HG-ESS.ConclusionsThis case highlights some of the diagnostic challenges posed by uterine mesenchymal neoplasms, and exemplifies the emerging histomorphologic, immunohistochemical, molecular and clinicopathologic features of the recently described HG-ESS with ZC3H7B-BCOR fusion. It adds to the body of evidence supporting the inclusion of BCOR HG-ESS as a sub-entity of HG-ESS within the endometrial stromal and related tumours subcategory of uterine mesenchymal tumors, as well as the poor prognosis and high metastatic potential of this tumor.

CASE REPORT- PRE AURICULAR SWELLING PRESENTED AS DERMATOFIBROSARCOMA

Background: Dermatofibrosarcoma protuberans a rare soft tissue tumour that involves the dermis, subcutaneous fat, and in rare cases muscle and fascia. Case Report: 34 yr old female patient presented with history of swelling in front of right ear since 2 years, associated with pain since 2 weeks , HRUSG neck reported as Neoplastic pathology and FNAC reported as benign spindle cell tumor. Patient underwent surgical excision of tumour. Frozen section sent was reported as synovial cell sarcoma or schwannoma. Hence on table superficial parotidectomy done. HPE showed Dermatofibrosarcoma protuberans . Conclusion: Dermatofibrosarcoma protuberans is considered intermediate-grade malignancy with low likelihood of metastasis hence treatment is complete surgical excision. As chance of recurrence is high regular follow up required.

Giant gastric stromal tumor with predominant cystic formation misdiagnosed as gastric cyst under endoscopic ultrasonography and fine-needle aspiration.

A 78-year-old man was admitted owing to 10 days of abdominal pain. He had a history of coronary heart disease, diabetes mellitus, and hypertension. Laboratory results, including tumor markers, blood amylase, and lipase, were unremarkable. During physical examination, a mass was palpated in the left upper abdomen (from the left costal arch to the umbilicus), which had an indistinct boundary and was poorly mobile. Esophagogastroduodenoscopy revealed a bulge in the gastric fundus with an unremarkable mucosa ([Fig. 1]). Computerized tomography revealed a huge abdominal cystic mass (23.3 × 14 × 22 cm), which had an indistinct boundary with the stomach ([Fig. 2]), and distinct boundaries with adjacent organs such as the liver, pancreas, etc. Endoscopic ultrasonography revealed a hypoechoic cystic lesion with scarred hyperechoic strip, and fine-needle aspiration was performed ([Video 1]). A rapid on-site evaluation was unremarkable. The cystic fluid analysis revealed a negative stringing test, normal amylase and lipase, slightly elevated CA125 and ferroprotein, with normal CEA, CA199, and AFP. Cell block and immunocytochemistry were also undiagnosed. Surgical resection was performed ([Fig. 3]), and 3000-mL cystic fluids were aspirated intraoperatively. Postoperative histology showed a spindle cell tumor ([Fig. 4]) with necrosis and cystic degeneration, and immunohistochemical results showed positive staining of CD117, DOG1 ([Fig. 5]), and CD34, with negative staining of SMA, S100, and Ki-67 index of 25 %, and mitoschisis of 8/50 HPF. Therefore, the final diagnosis was a high-risk gastrointestinal stromal tumor (GIST). He refused imatinib treatment and died within 2 years.

GAB1::ABL1 fusions define a distinctive soft tissue neoplasm, with variable perineurial differentiation, and a predilection for children and young adults.

Although well known as a fusion partner in hematological malignancies, fusion genes involving the ABL proto-oncogene 1 (ABL1), mapping to chromosomal region 9q34.12, have only been anecdotally reported in five soft tissue tumors. These neoplasms have been variously reported as perineurioma, angiofibroma, and solitary fibrous tumor, and all have harbored a GAB1::ABL1 gene fusion; however, the nosology and clinicopathological characteristics of soft tissue tumors carrying this rare fusion have not been delineated. We herein describe eight tumors containing the GAB1::ABL1 fusion and review previously reported cases in a series to define their morphological spectrum, address immunohistochemical evidence for a line of differentiation, with special reference to the presence or absence of a perineurial immunophenotype, and gather insight into their behavior. The patients included four females and four males, aged 13-37 years (median, 24 years). Two cases each originated in the shoulder area, trunk, hands, and lower extremities, with a size range of 1.5-8cm (median, 3.4cm). Four tumors were deep and four superficial. All tumors were morphologically similar, being composed of bland fibroblast-like spindle to ovoid cells diffusely arranged in a paucivascular fibrous to fibromyxoid stroma with variable resemblance to soft tissue perineurioma. Mitotic activity was generally low (0-8 mitoses in 10 high-power fields [HPFs]; median, 1). All lesions had at least focally infiltrative margins, but they otherwise lacked pleomorphism and necrosis. Immunohistochemistry showed focal reactivity for CD34 (5/7), epithelial membrane antigen (EMA) (3/8), claudin1 (2/3), GLUT1 (4/6), and S100 (2/7); other markers, including MUC4 (0/7), desmin (0/9), and smooth muscle actin(SMA) (0/4), were negative. RNA sequencing revealed a GAB1::ABL1 fusion in all cases with exon 6 of GAB1 fused to exon 2 of ABL1. Treatments included various forms of surgical intervention in seven cases; one tumor was biopsied only. Limited follow-up was available for five patients. One tumor regrew rapidly within 1 month to 1.5cm after an initial marginal excision and was re-excised with close margins. Four patients were disease-free at 1, 3, 14, and 25 months of follow-up. Metastases have not, to date, been observed. This series characterizes "GAB1::ABL1 fusion-positive spindle cell neoplasm" as a distinct entity, with overlapping features with soft tissue perineurioma and predilection for children and young adults.

Pediatric myofibroma/myofibromatosis of the soft tissue and bone: a clinicopathological analysis of 28 cases

Objective: To investigate the clinicopathological features, diagnosis and differential diagnosis of pediatric myofibroma/myofibromatosis of the soft tissue and bone. Methods: All cases of pediatric myofibroma/myofibromatosis of the soft tissue and bone diagnosed between January 2011 and December 2018 were retrieved from the surgical pathology records in the Department of Pathology, Beijing Jishuitan Hospital, Beijing, China. Clinical and radiological data were collected. H&E and immunohistochemistry were used to examine histological and immunophenotypic features and to make the diagnosis and differential diagnosis. The relevant literature was also reviewed. Results: Twenty-eight cases of pediatric myofibroma/myofibromatosis of the soft tissue and bone were respectively collected. The patients' ages ranged from 2 months to 14 years, with a mean age of 7 years. There were 7 females and 21 males. There were 12 cases located in soft tissue, including the finger (n=9), upper arm (n=1) and foot (n=2). There were 14 cases located in the bone of limb, including the femur (n=8), tibia (n=4), clavicle (n=2), fibula (n=2) and radius (n=1). There were 2 cases of myofibromatosis involving multiple bones. Radiology showed lytic lesions in the bone. The proliferation of spindle-shaped myofibroblasts arranged in fascicles with indistinct eosinophilic cytoplasm and bland nuclei, with no pleomorphism and cytological atypia. The characteristic histologic structure was the biphasic nodular growth pattern with cellular and paucicellular regions. The tumors might arrange in a hemangiopericytoma-like pattern. The stroma varied between dense fibrosis and myxoid changes. The reactive new bone formation and inflammatory cell infiltration also existed. Immunohistochemical study showed that the SMA was positive. The surgical resections were performed. One of the patients had tumor recurrence as a result of 11-month follow-up. Conclusions: The pediatric myofibroma/myofibromatosis of the soft tissue and bone is a very rare benign tumor and has a good prognosis. It has a characteristic morphology and its differential diagnosis from other spindle cell tumors could be made with the immunohistochemical analysis.

Identification of an Activating PDGFRA Deletion in a Novel Sinonasal Soft Tissue Neoplasm.

Spindle cell tumours in the sinonasal area are diagnostically challenging. We identified a neoplasm that defied histopathological classification using current criteria. The case was subjected to histopathological, immunohistochemical and molecular analysis using a large small variant DNA panel. The tumour comprised cytologically bland epithelioid spindle cells with a rich vasculature, which lack expression of actin and other smooth muscle markers, CD34 and beta-catenin. An activating insertion/deletion in exon 12 of the PDGFRA gene was detected. This alteration has previously been described in gastrointestinal stromal tumours and inflammatory fibroid polyps of the GI tract, but the site, histological, and immunophenotypic features in this tumour are distinct. We describe a novel sinonasal spindle cell tumour characterised by an activating insertion/deletion in exon 12 of PDGFRA. The diagnosis of PDGFRA-activated sinonasal spindle cell tumour should be considered in difficult to classify mesenchymal lesions at this site.

HISTOPATHOLOGICAL STUDY OF NEOPLASTIC BREAST LESIONS IN A TERTIARY CARE CENTRE.

We have studied 194 cases of neoplastic breast lesions over a period of 2 years (1 Jan 2020 to 31 December 2021) in MGM Medical college and Hospital, Aurangabad. The specimens were received in histopathology section of pathology department. Specimens were received in different forms such as Lumpectomy, trucut biopsy, simple mastectomy and MRM. Detailed gross examination of specimens (grossing of MRM: - according to AJCC protocol) followed by xation, thorough sampling and tissue processing. The different lesions were studied by histopathological examination and analysed. Neoplastic lesions were classied according to WHO classication (2017).Out of 194 cases, 75 cases had benign breast tumours and 119 had malignant tumours. Fibroadenoma (68 cases) was most common benign tumour followed by benign phyllodes (4cases), lactating adenoma (2 cases) and multiple ductal papilloma(1 case). Invasive carcinoma with no special type (104 cases) was most common malignant tumour. Special subtypes of invasive carcinoma found in our study were:- Invasive metaplastic carcinoma (1 case) Invasive lobular carcinomas (2cases), Invasive papillary carcinoma (1 case), Invasive mucinous adenocarcinoma (1 case), Solid papillary carcinoma (1 case), Invasive carcinoma with mucinous component (1 case) , Invasive carcinoma with neuroendocrine features (1 case) and Intracystic papillary carcinoma (2cases). Other malignant tumours included malignant phyllodes (2 cases) and malignant spindle cell neoplasm (3 cases). In our study, we found that malignant neoplasms were more common than benign neoplasms with Invasive breast carcinoma with no special type being the commonest malignant tumour. Histopathological study plays an important role in diagnosis of breast neoplasms and hence in treatment and prognosis.

Synchronous Retroperitoneal Schwannoma and Incidental Papillary Renal Cell Carcinoma: A Case Report

Background: Retroperitoneal schwannoma is a rare tumor rising from Schwann cells in peripheral nerve sheaths. Retroperitoneal schwannoma is really infrequent and has nonspecific symptoms and imperfect radiologic features, and is often identified histologically after surgery.
 Case Report: We report the case of a 73-year-old man presented with flank mass. Imaging shows a hypoechoic macro lobulated solid cystic mass in retroperitoneum. Intraoperatively, after complete resection of retroperitoneal mass, a suspected lesion in upper pole of right kidney was observed. Histopathology evaluation after surgery shows coexistence of a large retroperitoneal schwannoma and papillary renal cell carcinoma, type 1.
 Conclusion: Schwannoma should be considered in the differential diagnosis of retroperitoneal spindle cell tumor. Schwannoma coexisted with renal cell carcinoma in a patient is an unusual event. Thus, it can show the importance of appropriate evaluation before any surgery.

Rare Variants of Dermatofibrosarcoma Protuberans: Clinical, Histologic, and Molecular Features and Diagnostic Pitfalls.

Dermatofibrosarcoma protuberans (DFSP) is a dermal malignant mesenchymal tumor. Most variants are associated with a high risk of local recurrence and a low risk of metastasis. The classic histomorphology of this tumor is made up of uniform, spindle-shaped cells, arranged in a storiform pattern. Tumor cells characteristically infiltrate the underlying subcutis in a honeycomb pattern. Less common variants of DFSP have been identified: myxoid, pigmented, myoid, granular cell, sclerosing, atrophic, and fibrosarcomatous. Only the fibrosarcomatous variant has been shown to differ significantly from classic DFSP in terms of clinical outcome; fibrosarcomatous DFSP has been shown to be associated with a greater risk of local recurrence and metastatic potential than classic DFSP. However, the other variants may pose diagnostic difficulty as they resemble other types of spindle cell neoplasms, especially in small biopsy specimens. This article reviews the clinical, histologic, and molecular features of DFSP variants, as well as possible pitfalls in their diagnosis and how to resolve them.

Biphenotypic sinonasal sarcoma – a case report on a newly described entity

Malignant spindle cell tumours comprise ∼1% of all head and neck malignancies.1 One such entity is biphenotypic sinonasal sarcoma. This is a new entity first introduced in the WHO head and neck tumours classification in 2017. This can be easily misdiagnosed due to its rarity, novelty and morphology that overlaps with other diagnoses, both benign and malignant in the sinonasal tract. Expressing both neural and myogenic immunophenotypes and its monomorphic appearance due to its origin from a genetic fusion is atypical but characteristic.

Extensive Kaposi's sarcoma in a Patient with Acquired Immunodeficiency Syndrome: Case Report

Kaposi's Sarcoma (KS) is an angioproliferative neoplasm, the causative agent is human herpes virus 8 and the second most frequent tumor after non-Hodgkin lymphoma related to the human immunodeficiency virus (VIH). We present the case of a 40-year-old male with no history of chronic diseases, who began his condition with adenopathies in the bilateral inguinal region, adding a productive cough, lymphedema, and skin lesions with nodular characteristics and bleeding ulcers. A positive HIV test was reported, and a biopsy was performed, showing evidence of a spindle cell neoplasm compatible with KS. Laboratories with hemoglobin 8.3 mg/dL, platelets 239,000/uL, leukocytes 7.29/uL, glucose 76 mg/dL, creatinine 2.2 mg/dL, urea 80 mg/dL, albumin 1.69 g/dL, TGO 18 IU/L, TGP 5 IU/L, DHL 189 IU/L, viral load 283,259 copies and CD4 192 cells. Chest and abdomen computed tomography with evidence of pleural effusion, and multiple retroperitoneal and inguinal adenopathies. Starting concomitant retroviral treatment with liposomal doxorubicin, improving clinical status and laboratory parameters. HIV-infected people are at high risk of developing KS, early initiation of antiretroviral therapy, and maintenance of high CD4 cell counts are essential to reduce the incidence.