Track: Case Reports

Topic: Melanocytic Neoplasms

Abstract:

Pigmented epithelioid melanocytoma (PEM) is a rare, low to intermediate grade melanocytic neoplasm, characterized by genetic alterations resulting in the activation of the protein kinase A pathway, usually through either PRKAR1A-inactivation or PRKCA fusion. Historically, they were classified as animal-type melanoma and later grouped with epithelioid blue nevi (EBN) of Carney Complex as they displayed overlapping histomorphologic features. A 12-year-old boy with a history of eczema presented with a longstanding 8 x 4 mm intermittently tender, slow growing, blue papule on his lower back. Shave biopsy showed a predominantly dermal proliferation of pigmented epithelioid and dendritic melanocytes associated with numerous melanophages and an occasional mitotic figure. The predominantly monomorphic epithelioid-shaped melanocytes, which contained a central nucleolus, formed central sheets with more interstitial growth towards the periphery, entrapping collagen bundles. A background nevus was not identified. The lesional cells were positive for SOX10, HMB45, and Cyclin D1 and negative for BRAF p.V600E. Ki67 showed a mildly increased proliferation index and a PRKAR1A stain showed loss of expression, suggestive of PRKAR1A inactivation. RNA sequencing analysis revealed a SCARB1::PRKCA gene fusion. The diagnosis of a PEM was rendered, and the patient underwent a wide local excision one month later. We herein report a rare case of a PEM with a PRKCA fusion which has been identified in younger-aged patients. Differentiating PEM from other heavily pigmented melanocytic lesions by incorporating histomorphology and molecular findings is crucial for accurate classification and to ensure appropriate treatment.

Yuqing Xiong

Affiliation

Track

Refine Results

(252) A rare case of a pigmented epithelioid melanocytoma with a SCARB1::PRKCA fusion.