Agminated Clear Cell Tumor: An Impostor of PEComa and Distinctive Dermal Clear Cell Mesenchymal Neoplasm

Abstract

Cutaneous clear cell tumors are a heterogeneous group of cutaneous neoplasms, which may show a wide range of histogenesis. We report the clinicopathological features of an agminated clear cell tumor, arising in a 67-year-old man, otherwise asymptomatic, with distinct histopathological and immunohistochemical features, which did not fit into any existing diagnostic categories. The patient presented with several skin-colored papules at the lateral and posterior aspects of the neck, which on histopathological examination showed circumscribed lobular aggregates of clear cells within the dermis. The immunohistochemical marker panel performed showed diffuse expression of vimentin, NKI-C3, and CD64 while revealing marked negativity for factor XIIIa, CD10, CD13, CD14, CD34, CD68, CD163, lysozyme, HMB45, Renal Cell Carcinoma antigen, calponin, h-caldesmon, Anti-alpha smooth muscle actin antibody [1 A4], S100, and pancytokeratin, leading the authors to postulate a monocytic origin.

Clear Cell Proliferations of the Skin: A Histopathologic Review

“…Histopathological examination showed circumscribed lobular dermal aggregates of clear cells, which stained positive for vimentin, NKI-C3, and CD64 but were negative for a large series of relatively specific markers, leading the authors to postulate a monocytic origin of this neoplasm. 120 Primary Dermal Pleomorphic Liposarcoma Pleomorphic liposarcoma (PL) is the rarest histopathologic variant of liposarcoma, a heterogeneous group of malignant mesenchymal neoplasms with variable degrees of adipocytic differentiation. 121 Although PL usually affects deep soft tissues, a few primary dermal cases have been reported.…”

“…Histopathological examination showed circumscribed lobular dermal aggregates of clear cells, which stained positive for vimentin, NKI-C3, and CD64 but were negative for a large series of relatively specific markers, leading the authors to postulate a monocytic origin of this neoplasm. 120…”

Clear cell mesenchymal neoplasm with features mimicking metastatic renal cell carcinoma on routine histology but exhibiting a benign clinical course after 5 years of follow‐up

“…Specific melanocytic and epithelial immunohistochemical stains are negative. The routine histologic features may raise a differential diagnosis that includes other clear cell neoplasms such as metastatic carcinoma, acrospiroma, clear cell atypical fibroxanthoma, perivascular epithelioid cell tumor (PEComa) as well as clear cell variants of dermatofibroma and fibrous papule 2‐4 . Staining patterns and clinical features allow for differentiation.…”