Epithelioid Cytomorphology Research Articles

Sarcomas Harboring EWSR1::PATZ1 Fusions: A Clinicopathologic Study of 17 Cases

Soft tissue sarcomas harboring EWSR1::PATZ1 are a recently recognized entity with variable morphology and a heterogenous immunohistochemical profile. We studied 17 such tumors. The tumors occurred in 12 men and 5 women (median 50 years of age; range 15-71 years), involved the thoracoabdominal soft tissues (14 cases; 82%), lower extremities (2 cases;12%) and tongue (1 case; 6%), and ranged from 0.7-11.3 cm (median: 4.7 cm). All but one patient received complete surgical resection; 7 were also treated with neoadjuvant chemo/radiotherapy. All cases showed typical features of EWSR1::PATZ1 sarcoma, including uniform round to spindled cells, fibromyxoid matrix, fibrous bands, hyalinized vessels, and pseudoalveolar/microcystic spaces. Unusual features, seen in a subset of cases, included degenerative-appearing nuclear atypia, epithelioid cytomorphology, mature fat, abundant rhabdomyoblasts, high mitotic activity, and foci with increased cellularity and nuclear atypia. Positive immunohistochemical results were: desmin (16/17, 94%), MyoD1 (13/14, 93%), myogenin (6/14, 43%), GFAP (10/10, 100%), S100 protein (15/17, 88%), SOX10 (7/13,46%), keratin (10/17, 59%), CD99 (4/11, 36%), H3K27me3 (retained expression 9/9, 100%), p16 (absent expression; 1/4, 25%) and p53 (wild type 3/3, 100%). Fusion events included EWSR1 exon 8::PATZ1 exon 1 (14/17, 82%), EWSR1 exon 9::PATZ1 exon 1 (2/17, 12%) and EWSR1 exon 7::PATZ1 exon 1 (1/17, 6%). No evaluated tumor had alterations of CDKN2A/B and/or TP53, or MDM2 amplification. Clinical follow-up (16 patients: median, 13.5 months; range: 1-77 months) showed distant metastases in 1 patient (metastases at presentation) and no local recurrences. At last follow-up, 14 patients were disease free, 1 was alive with disease, 1 was dead of disease (at 13 months), and 1 had an indeterminant pulmonary nodule. We conclude that the morphologic spectrum of EWSR1::PATZ1 is broader than has been previously appreciated. Although more long-term follow-up is needed, the prognosis of these very rare sarcomas may be more favorable than previously reported.

PEComa of the Adrenal Gland: A Clinicopathologic Series of 7 Cases.

PEComas are a family of mesenchymal neoplasms composed of histologically distinctive perivascular epithelioid cells which demonstrate myomelanocytic differentiation. PEComas of the adrenal gland are very rare and can represent a considerable diagnostic challenge given their morphologic overlap with more common adrenal cortical neoplasms. We present the clinicopathologic features of 7 primary adrenal PEComas. The cohort comprised 5 male and 2 female patients with a median age of 63 years (range: 31 to 71y). One patient had Birt-Hogg-Dubé syndrome and another had Lynch syndrome; however, none had a history of tuberous sclerosis complex. Histologically, tumors showed nested and/or sheet-like growth and epithelioid cytomorphology with pale-to-eosinophilic granular cytoplasm. Two tumors had an admixed spindle cell component. There was a median of 4 mitoses per 10HPFs (range: 0 to 8). Necrosis was present in 4 tumors and lymphovascular invasion in 1. Four tumors were classified as malignant. By immunohistochemistry, tumors were positive for HMB-45 (3/7), MITF (3/3), Melan-A (3/7), smooth muscle actin (5/7), desmin (5/7), and caldesmon (1/1). Two tumors were positive for TFE3 (2/4). Inhibin and SF1 were negative in all tumors assessed (0/6). Of 3 patients with available clinical follow-up information, 1 patient developed locally recurrent and metastatic disease (at 18mo) and was alive with persistent disease at the last follow-up. Two patients had no recurrent or metastatic disease at the last follow-up (60 and 25mo). Although PEComas of the adrenal gland are rare, pathologists need to be alert to this entity in the differential diagnosis of primary adrenocortical neoplasms. In suspected cases, the judicious use of melanocytic and smooth muscle markers, in addition to TFE3 and markers of adrenocortical differentiation (such as SF1 and inhibin) can assist in diagnosis. As in PEComas arising at other visceral sites, an association with tuberous sclerosis complex seems to be uncommon.

Rhabdomyosarcoma With FUS::TFCP2 Fusion in the Mandible: A Rare Aggressive Subtype, but Can Be Misdiagnosed as Ossifying Fibroma.

Rhabdomyosarcoma (RMS) with TFCP2 rearrangement has been identified recently. This entity has a distinctive clinicopathologic features: a rapidly aggressive clinical course, a preference for the craniofacial bones, a spindle and epithelioid histomorphology, and positive immunohistochemistry for epithelial markers, ALK, and myogenic markers. RMS with TFCP2 rearrangement is rare and may be misdiagnosed as other spindle cell tumors. Here, we report a case of this entity arising in the mandible, which was initially diagnosed as ossifying fibroma in primary tumor in another hospital. A 26-year-old man presented with a recurred mass in the mandible for 1 month after the operation of mandibular tumor. The first excisional specimen was initially diagnosed as ossifying fibroma in another hospital. Histopathologic examination revealed the tumor with a hybrid spindle cell and epithelioid cytomorphology, spindle cells and spindle-to-epithelioid cells with eosinophilic and rich cytoplasm, with high-grade features, prominent nucleoli and some atypical mitosis. Immunohistochemical analysis revealed positivity for desmin, MYOD1, pan-keratin, ALK (5A4), ALK (D5F3). Based on the morphology and immunophenotype, molecular studies were performed, which revealed a FUS::TFCP2 fusion transcript, confirming the diagnosis of Rhabdomyosarcoma with FUS::TFCP2 fusion. Making a correct diagnosis is primarily dependent on awareness by the pathologist of this rare subtype of RMS and careful histopathological evaluation, supported by immunohistochemical and molecular analysis, to avoid potential diagnostic pitfalls.

POU2AF3-rearranged sarcomas: A novel tumor defined by fusions of EWSR1 or FUS to a gene formerly designated COLCA2.

Gene fusions involving EWSR1 or FUS as the 5' partner have been reported in a diverse array of sarcomas. Here, we characterize the histopathology and genomics of six tumors harboring a gene fusion between EWSR1 or FUS and POU2AF3, an understudied, putative colorectal cancer predisposition gene. Striking morphologic features reminiscent of synovial sarcoma were observed including a biphasic appearance with variable fusiform to epithelioid cytomorphology and staghorn-type vasculature. RNA sequencing demonstrated variable breakpoints in EWSR1/FUS along with similar breakpoints in POU2AF3 that encompassed a 3' portion of this gene. For cases in which additional information was available, the behavior of these neoplasms was aggressive with local spread and/or distant metastases. Although further studies are needed to confirm the functional significance of our findings, POU2AF3 fusions to EWSR1 or FUS may define a novel type of POU2AF3-rearranged sarcomas with aggressive, malignant behavior.

Epithelioid malignant peripheral nerve sheath tumor: A rare tumor with an unusual presentation in the ankle: A case report and literature review

Malignant peripheral nerve sheath tumor (MPNST) is a rare sarcoma with aggressive clinical zehavior. Epithelioid MPNSTs (EMPNSTs) are distinct and rare variant of MPNST. They are described by the World Health Organization and they account for <5% of these tumors and have unclear clinical behavior. Due to the rarity of the EMPNST and the overlapping features and similarity with other tumors exhibiting epithelioid cytomorphology, EMPNSTs impose a diagnostic challenge. Therefore, it is critical to be aware of this entity and other mimickers to reach the correct diagnosis. Hence, this is a case of a 45-year-old lady who presented with persistent left ankle swelling for 2 years. A biopsy was performed, which confirmed the diagnosis of EMPNST. The aim of reporting this case of this rare tumor with this presentation was to help both pathologists and orthopedic oncology surgeons to understand the behavior of this tumor and help differentiate it from mimickers, and enrich interested readers’ knowledge with the presented literature review.

Epithelioid angiosarcoma of the duodenum: a case report

BackgroundAngiosarcomas are rare malignant tumors that arise from the endothelium of blood vessels. They occur most commonly in the skin and soft tissue, and less commonly in the breast, liver, bone, and spleen. Gastrointestinal angiosarcomas are extremely rare. Herein, we present a case of duodenal epithelioid angiosarcoma that was treated with surgical resection.Case presentationA 68-year-old man presented with a 1-month history of fatigue and hypotension. He visited the outpatient clinic for a routine follow-up. Laboratory examination revealed anemia. Esophagogastroduodenoscopy revealed multiple duodenal lesions with central ulceration. A biopsy showed a sheet-like arrangement of large round and spindle-shaped tumor cells that were positive for CD31. Based on the histological and immunohistochemical staining findings, an epithelioid angiosarcoma was diagnosed. Computed tomography (CT) and positron emission tomography–CT revealed no lymph node metastasis or distant metastasis. Radical subtotal stomach-preserving pancreatoduodenectomy with lymphadenectomy was performed. After removing the specimen, reconstruction was performed using the Child procedure. Grossly, two dark-red polypoid tumors were found in the second portion of the duodenum. Histological evaluation revealed proliferation of malignant round and polygonal cells arranged in sheets and spindle-like cells arranged in bundles. Vasoformative structures were recognized as slit-like spaces containing red blood cells. Immunohistochemical staining demonstrated that the tumor cells were positive for CD31. These findings confirmed the diagnosis of epithelioid angiosarcoma in the duodenum. The patient’s postoperative course was uneventful. The patient was discharged on postoperative day 19 without any complications. At a follow-up examination in the outpatient clinic at postoperative 4 months, no evidence of recurrence was detected.ConclusionThe present report describes a case of duodenal epithelioid angiosarcoma. Duodenal angiosarcomas may cause anemia and gastrointestinal bleeding. Because angiosarcomas sometimes show epithelioid cytomorphology, immunohistochemical analysis is useful for confirming the diagnosis.

Epithelioid Sarcoma: An overview with emphasis on its differentiation from morphologic mimics

Epithelioid sarcoma (ES) is a malignant mesenchymal neoplasm that exhibits epithelioid cytomorphology and a predominantly epithelial phenotype. The principal types based on histopathological features and location; include the classic or conventional type (CES) and the proximal type (PES). The aim of the study was to analyze our cases of ES regarding clinical, pathological and immunohistochemical features.This is a retrospective study. Seven cases of ES were included in the study. Clinical and pathological details were retrieved from patient records. Details like site, size, histopathological type and IHC features of the tumors were studied. Out of seven, five were PES and two were CES. There were six males and one female; with age ranging from 12 to 68 years. Total five tumors involved extremities. One was noted at a rare site, paratesticular region. Three tumors were larger than 5 cm in greatest dimension. On immunohistochemistry (IHC), all the tumors were reactive for CK, EMA, Vimentin, Ca 125 and showed loss of nuclear expression of INI1. CD 34 was expressed in 6 out of 7 cases.ES is a rare aggressive malignant tumor with dismal prognosis. It is often misdiagnosed because of nonspecific clinical features at presentation. Helpful clues in diagnosis are tumors in young males with epithelioid and/or spindle cell morphology, Rhabdoid cells and granuloma like central necrosis. Co-expression of epithelial and mesenchymal markers along with reactivity for CD34 and Ca 125 and loss on INI1 expression on IHC substantiate the diagnosis of ES.

Biopsy for molecular risk stratification in uveal melanoma: Yields and molecular characteristics in 119 patients.

Prognostic cytological and molecular features of uveal melanoma have been well researched and are essential in management. Samples can be obtained in vivo through fine needle aspirate biopsy, vitrector cutter, forceps or post-enucleation for off-site testing. This study aims to examine cytological and chromosome microarray yields of these samples. A retrospective cohort analysis of 119 uveal melanoma biopsies submitted to our laboratory. Samples included those taken in vivo (n=57) and post-enucleation (n=62). Patient and tumour features were collected including age, sex, primary tumour location, basal diameter and tumour height. Prognostic outcomes measured include cell morphology, chromosomal status and immunohistochemistry. Post-enucleation biopsies accounted for just over half of our samples (52%). Post-enucleation samples had a more successful genetic yield than in vivo biopsies (77% vs. 50%, p=0.04) though there was no difference for cytological yields. There was no difference in cytological or microarray yields between instruments. The vitrector biopsy group had the smallest tumour thickness (5 mm vs. 10 mm [fine-needle aspirate biopsy], p=0.003). There was a strong correlation between monosomy 3, BAP1 aberrancy and epithelioid cell type in post-enucleation samples (Tb =0.742, p=0.005). However, epithelioid morphology was not associated with either monosomy 3 (p=0.07) or BAP1 aberrancy (p=0.24) for in vivo biopsies. All three biopsy instruments provide similar cytological yields as post-enucleation sampling, although post-enucleation samples had a more successful chromosome microarray yield. Epithelioid cytomorphology alone is insufficient for prognostication in in vivo biopsies, immunohistochemistry would be a useful surrogate test.

Anaplastic Thyroid Carcinoma: Cytomorphologic Features on Fine-Needle Aspiration and Associated Diagnostic Challenges.

Anaplastic thyroid carcinoma (ATC) is an aggressive malignancy, and early diagnosis, often aided by fine-needle aspiration (FNA), is key to improving patient prognosis. While the current literature describes some of the cytologic features (CFs) of this entity, a comprehensive examination of the CFs has not yet been performed. We retrospectively searched our electronic database for ATC cases with available slides between January 2008 and December 2019. Cases were examined for 22 CFs and compared with a control group of differentiated thyroid carcinoma. A total of 18 ATC cases meeting our inclusion criteria were identified. Most cases showed moderate to high cellularity (83%) and epithelioid cytomorphology (83%). Architecture included either predominantly groups/clusters of tumor cells (56%) or single tumor cells (44%). The other CFs were as follows: nuclear enlargement (100%), nuclear crowding (89%), nuclear membrane irregularities (100%), multinucleated tumor cells (33%), and background acute inflammatory cells (50%). Of the CFs examined, statistically significant differences between ATC and the control groups were found in the following: nuclear pleomorphism, coarse/clumped chromatin, macronucleoli, apoptosis, and necrosis. Identification of key CFs in FNA coupled with the clinical history aids in the diagnosis of ATC and helps distinguish it from other mimickers.

Proximal Type - Epithelioid Sarcoma- A Rare And Aggressive Soft Tissue Neoplasm

Abstract Introduction/Objective Epithelioid Sarcoma is a rare malignant soft tissue neoplasm that is well known for local recurrence, regional lymph node involvement, and metastasis. It accounts for less than one percent of all sarcomas. Two subtypes of epithelioid sarcoma are described: the conventional or classic subtype and the proximal subtype, with the classic type being more common than the proximal type. We present a case of proximal epithelioid sarcoma involving the inguinal region, in which the patient presented with the history of weight loss for one year and a slow- growing inguinal mass for the last few months. The biopsy was done in an outside hospital and showed carcinoma of unknown origin. Imaging also failed to reveal any clear source of this mass. Methods The mass was resected and sent to pathology, where H&E staining and immunohistochemistry was done for diagnosis. Results The H&E sections of the left inguinal mass showed proliferation of large epithelioid cells with a moderate amount of cytoplasm, vesicular nuclear chromatin and prominent nucleoli. Mitosis was also seen. Necrosis was not identified. Immunohistochemical staining was done and revealed that the tumor cells were immunoreactive for epithelial marker cytokeratin AE1/AE3 and showed loss of INI-1. Tumor cells were also negative for Myogenin, ERG, HMB-45, MART-1, Myo-D1, S100, and SMA. Considering the cytomorphology and immunophenotypic findings the diagnosis of epithelioid sarcoma, proximal type was made. Conclusion Epithelioid sarcoma is a malignant mesenchymal neoplasm with epithelioid cytomorphology and phenotype. Among the two types of epithelioid sarcoma, the proximal type is reported about 50% less than the classic type and is associated with aggressive behavior and worse prognosis. The classic cytomorphology and immunohistochemistry findings helped us in making the diagnosis in this case.

Epithelioid Fibrous Histiocytoma: A Concise Review.

Epithelioid fibrous histiocytoma (EFH) is a rare lesion believed to arise from dermal microvascular unit fibroblasts and dendritic histiocytes. EFH has long been considered a morphologic variant of benign fibrous histiocytoma (dermatofibroma), with prominent epithelioid cytomorphology that can mimic both vascular and melanocytic neoplasms. The molecular basis for the relationship between EFH and benign fibrous histiocytoma has remained largely unknown, with some authors suggesting that EFH represents an entity that is biologically distinct from benign fibrous histiocytoma. Recent molecular studies have identified the presence of recurrent anaplastic lymphoma kinase (ALK) gene rearrangements, a phenomenon that has not been described in benign fibrous histiocytoma. These new molecular findings highlight the uniqueness of this rare tumor and may prove useful as a diagnostic tool for differentiation from other histologic mimics.

Uveal Melanoma Treatment and Prognostication.

Approximately 90% of uveal melanoma develop in the choroid, with the remainder arising in the ciliary body or the iris. The treatment of uveal melanoma is aimed at conserving the eye and useful vision, and, if possible, preventing metastatic disease. Enucleation is now reserved for tumors that are large and/or involve the optic disc, having largely been replaced by various forms of radiotherapy (plaque brachy-therapy, proton beam or stereotactic radiotherapy) and laser therapy. Whereas iridectomy and iridocyclectomy are widely performed, transscleral exoresection of choroidal tumors is performed only in a few centers because it requires special skills and hypotensive anesthesia. Transretinal endoresection using vitrectomy equipment is easier but controversial because of concerns about tumor seeding. Long-term postoperative surveillance is necessary to identify and treat local tumor recurrence and any other complications, such as radiation-induced morbidity, and to provide counseling to the patient. Factors predicting metastasis include older age, large tumor size, ciliary body involvement, extraocular spread, epithelioid cytomorphology, chromosome 3 loss and chromosome 8q gain, class 2 gene expression profile, loss of BRCA1-associated protein-1 (BAP1), and the presence of inflammation. Prognostication is enhanced by multi-variable analysis combining clinical, histologic, and genetic factors, also taking the patient's age and sex into account. As there is a lack of options for treating metastases, much research is focused on identifying potential therapeutic targets.

Epithelioid Haemangioendothelioma with Actin+/Cytokeratin+ Myoblast-Like Cells: Report of a Case

An unusual case of epithelioid hemangioendothelioma (EHE) with immunohistochemical positivity for cytokeratin (CK), alpha-smooth muscle actin, and calponin (CALP) is presented. The lesion occurred in a 43-year-old man in the right frontal region, with clinical suspicion for an epidermoid cyst. It was excised completely. Grossly, an 8 mm nodule was well circumscribed, soft, and it had gray cut surface. Histologically, typical features of EHE were seen, such angiocentric localization, epithelioid cytomorphology with mild atypia, myxohyaline stromal matrix, a few slit-like vascular channels, and isolated vacuolated cells. In addition, the stroma contained numerous spindle cells resembling myoblasts or myofibroblasts. They showed, besides scattered positivity for vascular markers, focal positivity for CALP and diffuse strong expression of alpha-smooth muscle actin and pancytokeratin AE1/AE3. This observation of numerous actin+/CK+cells is unusual. The lesion resembled other CK-positive vascular tumors and actin-positive myofibroblastic lesions, all of which has to be considered in differential diagnosis.

ALK rearrangement and overexpression in epithelioid fibrous histiocytoma

Epithelioid benign fibrous histiocytoma, also known as 'epithelioid cell histiocytoma,' has traditionally been considered a morphologic variant of cutaneous fibrous histiocytoma (dermatofibroma). In addition to its characteristic epithelioid cytomorphology, several phenotypic differences suggest that epithelioid fibrous histiocytoma may differ biologically from other variants. Recently, ALK rearrangement was described in two cases of epithelioid fibrous histiocytoma and separately in two cases reported as 'atypical' fibrous histiocytoma (with epithelioid features), with corresponding ALK expression detectable by immunohistochemistry. The goals of this study were to determine the frequency of ALK expression by immunohistochemistry in epithelioid fibrous histiocytoma, to determine its value for the diagnosis of epithelioid fibrous histiocytoma among variants and other histologic mimics, and to evaluate ALK gene rearrangement in epithelioid fibrous histiocytoma. ALK protein expression was evaluated in whole tissue sections from 33 epithelioid fibrous histiocytomas, 41 other cases of fibrous histiocytoma (11 conventional and 10 each cellular, atypical, and aneurysmal types), 10 cutaneous syncytial myoepitheliomas, and 5 atypical fibroxanthomas, using a mouse anti-ALK monoclonal antibody. Fluorescence in situ hybridization (FISH) was performed using break-apart probes. In total, 29/33 (88%) cases of epithelioid fibrous histiocytoma showed diffuse cytoplasmic ALK expression. Staining was moderate to strong in intensity in all cases except one, which showed diffuse weak expression. All other tumor types were negative for ALK expression. FISH demonstrated ALK rearrangement in all ALK-immunoreactive cases evaluated (n=13), and not in one ALK expression-negative epithelioid fibrous histiocytoma successfully examined. In conclusion, the majority of epithelioid fibrous histiocytomas demonstrate ALK expression and ALK gene rearrangement. ALK expression is not seen in other variants of fibrous histiocytoma, providing a useful diagnostic tool to distinguish epithelioid fibrous histiocytoma from most histologic mimics. The expression of ALK suggests that epithelioid fibrous histiocytoma is a biologically distinct tumor type, unrelated to conventional fibrous histiocytoma and histologic variants.

Alterations of the mTOR pathway in hepatic angiomyolipoma with emphasis on the epithelioid variant and loss of heterogeneity of TSC1/TSC2.

To determine the significance of the epithelioid type and the corresponding molecular alterations in hepatic angiomyolipoma (AML). We retrieved 24 samples of hepatic AML to delineate the clinicopathological features and the immunohistochemical expression of components in the mTOR pathway, and employed microsatellite markers to analyse allelic imbalances in the TSC1 and TSC2 regions. Myomatous AML was the most common type, and a predominantly epithelioid cell population was observed in 50% of the samples. Two-thirds of all samples contained <20% of fat tissue. Four cases of monotypic epithelioid AML were discovered without prognostic implications. Elevated phospho-p70S6 kinase expression was noted in 19 samples in the absence of phospho-AKT activity. Loss of heterogeneity (LOH) of TSC1/TSC2 was found in 15 samples. As compared wityh syndromic AML samples, sporadic AML samples showed LOH of microsatellite markers to a limited extent. Only four samples had increased β-catenin expression in the context of concurrent high expression of phospho-p70S6 kinase and phospho-S6 (P=0.018). The low fat content and epithelioid cytomorphology in hepatic AML potentially obstruct preoperative and pathological diagnosis. Alteration of the mTOR pathway and LOH of the tuberous sclerosis complex genes is a frequent pathogenesis in hepatic AMLs.

Comparative Analysis of Atypical Spitz Tumors With Heterozygous Versus Homozygous 9p21 Deletions for Clinical Outcomes, Histomorphology, BRAF Mutation, and p16 Expression

Studies have shown that atypical Spitz tumors (ASTs) with homozygous deletions in 9p21 have worse prognosis than those without this finding. Conversely, numerous studies have shown that a range of other copy number aberrations including isolated 6q23 or 3p21 loss may be seen in ASTs without conferring higher risk for aggressive behavior. We studied 31 cases of ASTs with heterozygous 9p21 loss and hypothesize that heterozygous 9p21 loss in ASTs does not confer an increased risk for aggressive behavior. We compared clinical, histopathologic, and immunohistochemical features of 31 ASTs with heterozygous 9p21 deletions with 30 ASTs with homozygous 9p21 deletions. No ASTs with heterozygous 9p21 deletions resulted in distant metastasis. Severe cytologic atypia, a predominance of epithelioid cytomorphology and increased dermal mitotic activity were more frequent in ASTs with homozygous deletions versus ASTs with heterozygous deletions (P=0.0003, 0.0004, and 0.042, respectively). Expression of p16 and mutated BRAF proteins was also evaluated in 17 conventional (nonspitzoid) melanomas with homozygous 9p21 loss and the 2 groups of ASTs. Expression of p16 was retained in 67% of ASTs with heterozygous loss, whereas among ASTs with homozygous loss, 100% of cases had areas with complete loss of staining. Mutated BRAF protein expression was detected in 53% of conventional melanomas, in none of the ASTs with heterozygous loss, and in 1 AST with homozygous loss (P=0.0007 between homozygous ASTs and the conventional melanomas). Coexisting BRAF mutation and 9p21 deletion was more common in conventional melanomas than in ASTs with heterozygous or homozygous 9p21 deletion. BRAF mutation was highly uncommon among the ASTs.

Primary pseudomyogenic haemangioendothelioma of bone

Pseudomyogenic haemangioendothelioma is a recently described vascular neoplasm that occurs most commonly in the soft tissue of distal extremities of young adults. Occurrence outside the somatic soft tissue has not been described thus far. We present here a unique case of pseudomyogenic haemangioendothelioma that arose in the long tubular bones of the lower extremity. The initial open biopsy was interpreted as a fibrous histiocytoma. However, the curettage specimen showed prominent epithelioid cytomorphology with a striking rhabdomyoblast-like appearance. By immunohistochemistry, the linear membranous staining of CD31 was highly suggestive of endothelial differentiation of the tumour cells. To the best of our knowledge, this case represents the first example of primary pseudomyogenic haemangioendothelioma of bone. Clinical and pathological correlation with application of immunohistochemistry is mandatory in establishing the correct diagnosis and excluding tumours with overlapping features.

Ossifying fibromyxoid tumor — Diagnostic challenge for a cytopathologist

Ossifying fibromyxoid tumor — Diagnostic challenge for a cytopathologist

Cytologic Features of Epithelioid Hemangioendothelioma

To determine cytologic features of epithelioid hemangioendothelioma (EHE) that would enable accurate diagnosis, we evaluated fine-needle aspiration biopsy (FNAB) smears from 11 histologically confirmed EHEs. The variably cellular smears comprised dispersed single cells and occasional cell aggregates. Dense stromal fragments were present in association with some tissue fragments. The cells were epithelioid, containing moderate or large amounts of dense cytoplasm. Nuclei exhibited mild pleomorphism, and nuclear grooves were identified in all cases. At least occasional intranuclear pseudoinclusions (INPIs) and intracytoplasmic lumina (ICLs) were present in all cases and in 9 cases (82%), respectively, and rare erythrocytes were seen within ICLs in 5 cases (45%). Mitotic figures were identified in 4 cases (36%). The background was bloody in 6 cases (55%) and contained hemosiderin and/or hemosiderin-laden macrophages in 5 cases (45%). The combination of the following features in FNAB samples should raise strong suspicion for EHE: predominantly dispersed single cells with occasional cohesive cell clusters; epithelioid cytomorphology; dense cytoplasm with well-defined cytoplasmic borders; ICLs (with or without erythrocytes), INPIs, and nuclear grooves. The presence of these features should prompt correlation with clinical, radiologic, and histologic features and immunohistochemical evaluation using vascular markers.

EMA positivity in epithelioid fibrous histiocytoma: a potential diagnostic pitfall

Epithelioid fibrous histiocytoma (EFH) represents a morphologic variant of cutaneous fibrous histiocytoma (FH) but can lack many characteristic features. The presence of epithelioid cytomorphology may mimic other dermal neoplasms. Our anecdotal experience of epithelial membrane antigen (EMA) expression in some examples of EFH has caused diagnostic difficulty. Our aim was to examine the immunohistochemical profile and incidence of EMA expression in EFH. Forty-four cases of EFH were retrieved from consultation files. Clinicopathologic and immunohistochemical features were evaluated. Membranous EMA positivity was found in tumor cells in 27/42 cases (64%). Focal positivity for factor XIIIa was found in 10/14 (71%) and D2-40 in 14/27 (52%). Scattered smooth muscle actin (SMA)-positive tumor cells were seen in 11/43 (25%). Focal positivity for claudin-1 was found in 3/42 (7%). CD163 staining highlighted stromal macrophages; however, in five cases it was difficult to exclude focal staining of tumor cells. Tumor cells were consistently negative for pan-keratin, AE1/AE3, S100, CD31, CD34, CD68, desmin, p63, GFAP and CD45/LCA. Frequent EMA expression in EFH represents an unexpected finding and constitutes a potential diagnostic pitfall. Although of uncertain significance, this finding, when combined with established morphologic differences, raises the possibility that EFH is unrelated to classic FH.