Malignant perivascular epithelioid cell tumor (‘PEComa’): a case report and literature review of cutaneous/subcutaneous presentations

Abstract

Perivascular epithelioid cell (PEC) tumors, also called 'PEComas,' are distinct tumors showing PEC differentiation with characteristic histologic and immunophenotypic features. PEComas are rare tumors documented in the literature presenting in numerous anatomic sites including the thorax, abdomen, pelvis, soft tissue and skin. Criteria for malignancy does not exist for the subset of PEComas that pursue an aggressive clinical course. Herein, we present an unusual case of a malignant PEC tumor presenting as a scalp nodule in a patient with a prior diagnosis of 'melanoma' based upon the immunophenotypic profile of an excised enlarged cervical lymph node. The purpose of this case presentation is to further describe the rare clinical manifestations of a subcutaneous PEC tumor, emphasize the malignant potential of this entity, and review the literature focusing upon clinicopathologic features of cutaneous/subcutaneous PEComas.

PEComa of the Nose: Report of a Case with Immunohistochemical and Ultrustructural Studies and a Review of the Literature

“…A subset of PEComas have been reported to exhibit a malignant behaviour and pursue an aggressive clinical course [24,25]. Provisional criteria for malignany have been proposed based on worrisome features of large size ([5 cm), high nuclear grade and cellularity, necrosis and [1 mitotic figures/50 HPF [19].…”

Perivascular Epithelioid Cell Tumors (PEComas) of the Head and Neck: Report of Three Cases and Review of the Literature

“…Other than a mass effect, no other specific signs or symptoms were noted. PEComas are rare in the head and neck [7][8][9][10][11][12][13][14][15][16][17], and those arising in the nasal cavity and larynx are even more unusual [7,12]. The common morphologic features observed in all three tumors included: large polygonal to epithelioid cells with clear or eosinophilic granular cytoplasm, centrally located nuclei with vesicular chromatin, and occasional nucleoli; a predominantly nested growth pattern associated with a delicate vascular stroma, similar to the vessels seen in clear cell renal cell carcinomas and paragangliomas; and a zone of subepithelial sparing.…”

“…Based on our review of the English literature, we identified 13 cases [7][8][9][10][11][12][13][14][15][16][17] of primary head and neck PEComas (excluding examples described as AML). Including our three cases, this number now consists of 16 tumors (Table 1).…”

“…Adequate follow-up was reported in 14 patients. Two patients (one skull base and one scalp) behaved in an aggressive fashion with distant or loco-regional metastases and one patient (skull base) died of disease-related causes [8,16]. Therefore, 14% of head and neck PEComas, with available follow-up, behaved aggressively with loco-regional or distant metastases and only 7% died of disease.…”

“…A vast majority of reported PEComas seem to behave in a benign fashion, although a malignant course with local recurrences and distant metastases has been reported [8,10,16,27,28]. Predicting the behavior of PEComas based on histology alone is challenging.…”