Spindle cell variant of epithelioid sarcoma: an easily misdiagnosed tumour

Epithelioid Sarcoma: Diagnostic Features and Genetics

Epithelioid sarcoma (ES) is a rare, aggressive soft-tissue neoplasm of uncertain differentiation, characterized by nodular aggregates of epithelioid cells, which are immunoreactive to cytokeratins (CKs) and epithelial membrane antigen, and often for CD34. It has a propensity for multifocal disease at presentation, local recurrence, and regional metastasis. These are aggressive neoplasms with particularly poor prognosis after regional or distant metastatic disease, for which surgical resection is still the mainstay of treatment, and options for patients with metastatic disease remain undefined. There are 2 distinct variants: classic ES, which typically presents as a subcutaneous or deep dermal mass in the distal extremities of young adults and comprises nodular distributions of relatively uniform epithelioid cells with central necrosis, and the proximal variant, which has a predilection for proximal limbs and limb girdles and the midline of the trunk, which is composed of sheets of larger, more atypical cells with variable rhabdoid morphology. Both classic and proximal-type ESs are associated with the loss of SMARCB1/INI1 protein expression, but appear otherwise molecularly relatively heterogeneous. We review classic and proximal-type ES, discussing morphology, immunohistochemical and genetic findings, the differential diagnosis, and the future potential for targeted therapies.

An aggressive case of pseudomyogenic haemangioendothelioma of bone with pathological fracture and rapidly progressive pulmonary metastatic disease: case report and review of the literature

Pseudomyogenic haemangioendothelioma (PMH) is a rare recently described vascular tumour typically presenting with soft tissue disease in distal extremities of young adults. Multi-focal and multi-layered involvement is commonly recognised. The majority of cases described so far have shown an indolent clinical course and distant metastatic spread is rare. We report a case of PMH in an 82-year-old male diagnosed following a pathological fracture of the distal tibia. Further bone lesions were identified in the fibula, patella and distal femur. The patient was found to have multiple nodules suspicious for pulmonary metastases on a CT scan at the time of diagnosis that showed significant progression at a follow-up scan 4 weeks later. To our knowledge, this is the first reported case of PMH presenting with a pathological fracture. The rapid progression of bone and distant metastatic disease in this case is highly unusual given the typically indolent clinical course reported in the literature to date.

Penile pseudomyogenic hemangioendothelioma/epithelioid sarcoma-like hemangioendothelioma with a novel pattern of SERPINE1-FOSB fusion detected by RT-PCR--report of a case

We experienced a rare case of penile mesenchymal tumor in a 43-year-old Japanese man. At least three nodules were observed around the penis. The tumors were composed of spindle- to oval-shaped atypical cells with and without prominent nucleoli. These cells were like myogenic cells, but negative for myogenic markers. They were positive for endothelial markers, such as ERG, Fli1 and CD31. They were also positive for nuclear and cytoplasmic FOSB which are not expressed in epithelioid hemangioendothelioma or epithelioid sarcoma. These pathological and immunohistochemical findings strongly suggested pseudomyogenic hemangioendothelioma/epithelioid sarcoma-like hemangioendothelioma (PHE/ES-HE). Since a recent report directly proved that two cases of PHE/ES-HE have SERPINE1-FOSB fusion gene by reverse transcription-polymerase chain reaction (RT-PCR), we examined whether the fusion gene is present or not in the present case by RT-PCR using fresh frozen surgical material. Sequencing of the PCR product revealed that this case has SERPINE1-FOSB fusion. The fusion pattern of our case was different from those of two previously reported cases. In our case, 86 nucleotides of SERPINE1 intron 1 were inserted between SERPINE1 exon 1 and the middle portion of FOSB exon 1, and a putative translation start codon was identified in SERPINE1 intron 1. Thus, this is the third case of PHE/ES-HE with SERPINE1-FOSB fusion proved by RT-PCR.

Epidermotropic metastatic epithelioid sarcoma: a potential diagnostic pitfall

Epithelioid sarcoma (ES) represents an aggressive soft tissue tumor with varied morphologic and histopathologic presentations that typically elicits a broad differential diagnosis, including granuloma annulare, necrobiotic granuloma, fibrous histiocytoma, synovial sarcoma, amelanotic melanoma and poorly differentiated primary cutaneous and metastatic adenocarcinoma. ES is characterized microscopically by a nodular arrangement of abundant, deeply eosinophilic, polygonal tumor cells with frequent central necrosis and hemorrhage, rare mitotic figures and minimal pleomorphism. At the periphery, tumor cells are spindle shaped and may exhibit frequent local infiltration along tendons, fascial planes and neurovascular bundles. Immunohistochemistry typically reveals expression of both epithelial and mesenchymal antigens, such as cytokeratin and vimentin, respectively. The absence of a connection between tumor cells and the overlying epidermis, with or without an in situ carcinoma component, typically rules out a primary cutaneous squamous cell carcinoma. We report a case of stage IV proximal-type ES that mimicked molluscum contagiosum clinically and was histopathologically reminiscent of invasive squamous cell carcinoma because of attachment and colonization of the overlying epidermis. The case represents an unusual pathologic presentation of ES and highlights potential pitfalls in establishing the diagnosis.

Pseudomyogenic (epithelioid sarcoma-like) hemangioendothelioma: characterization of five cases

OBJECTIVE

To describe the imaging and histopathology of pseudomyogenic hemangioendothelioma.

MATERIALS AND METHODS

Five cases of pseudomyogenic hemangioendothelioma, which presented over the last 5 years, were retrieved from the files of the Royal National Orthopaedic Hospital. The imaging and histopathology were reviewed in all cases. Magnetic resonance imaging, which was available from all cases, was assessed for the following features: the number of lesions, location in soft tissue (superficial and or deep/subfascial) and bone, and the signal characteristics and morphology of individual lesions. Immunohistochemistry was performed in all cases to characterize the lesions.

RESULTS

Four of the five patients had multiple lesions involving a single limb. Bone was involved in 3 of the 5 individuals. All tumors diffusely expressed ERG and cytokeratins AE1/3, but not MNF116. CD31 was weakly positive in 4 cases. INI-1 expression was retained in all cases. Imaging features included ill-defined, infiltrative lesions in subcutaneous fat with extension to the adjacent skin, poor- to well-defined intramuscular nodules and predominantly intracortical focal bone lesions with rare medullary involvement.

CONCLUSION

Pseudomyogenic hemangioendothelioma represents a distinct recently characterized tumor type presenting in young adults, with a tendency towards multicentric bone and soft tissue involvement.

Hemangioendothelioma

Hemangioendothelioma is the term used to name those vascular neoplasms that show a borderline biological behavior, intermediate between entirely benign hemangiomas and highly malignant angiosarcomas. Although originally spindle cell hemangioendothelioma was proposed as a specific clinicopathologic variant of hemangioendothelioma, currently, it is considered as an entirely benign lesion, and thus, the name spindle cell hemangioma seems to be the most accurate for this lesion. Authentic hemangioendotheliomas involving the skin and soft tissues include papillary intralymphatic angioendothelioma (also known as Dabska tumor), retiform hemangioendothelioma, kaposiform hemangioendothelioma, epithelioid hemangioendothelioma, pseudomyogenic hemangioendothelioma (also known as epithelioid sarcoma-like hemangioendothelioma), and composite hemangioendothelioma. Each of these neoplasms exhibit characteristic histopathologic features. The most characteristic finding of papillary intralymphatic hemangioendothelioma consists of papillary tufts, with a central hyaline core lined by hobnail-like endothelial cells protruding into the lumina. Retiform hemangioendothelioma is an infiltrative neoplasm composed of elongated arborizing vessels, arranged in an anastomosing pattern that resembles that of the rete testis, and lined by a single layer of hobnail-like endothelial cells that protrude within the narrow lumina. Kaposiform hemangioendothelioma is composed of several solid poorly circumscribed nodules, and each nodule is composed of a mixture of small capillaries and solid lobules of endothelial cells arranged in a glomeruloid pattern. A frequent finding consists of the presence of areas of lymphangiomatosis adjacent to the solid nodules. Epithelioid hemangioendothelioma is composed of cords, strands, and solid aggregates of round, oval, and polygonal cells, with abundant pale eosinophilic cytoplasm, vesicular nuclei, and inconspicuous nucleoli, embedded in a fibromyxoid or sclerotic stroma. Many neoplastic cells exhibit prominent cytoplasmic vacuolization as an expression of primitive vascular differentiation. Pseudomyogenic hemangioendothelioma is a poorly circumscribed, fascicular lesion with infiltrative borders composed of round or oval neoplastic cells, with vesicular nuclei and inconspicuous nucleoli, and ample homogeneous eosinophilic cytoplasm, giving them a rhabdomyoblastic appearance. Finally, composite hemangioendothelioma is the term used to name locally aggressive vascular neoplasms of low-grade malignancy showing varying combinations of benign, low-grade malignant, and high-grade malignant vascular components. From the immunohistochemical point of view, proliferating cells of all hemangioendotheliomas express a lymphatic endothelial cell immunophenotype. Most hemangioendotheliomas are low-grade vascular neoplasms, with a tendency to recur locally and a low metastatic potential, mostly to regional lymph nodes. Epithelioid hemangioendothelioma, especially large lesions and those located in deep soft tissues, seems to have a more aggressive biological behavior.