Track

Case Reports

Abstract

Herein we report an unusual dermal tumor with PTEN::RNLS translocation.

A 52-year-old male presented with a 1.5 cm painful fingertip nodule. On histopathology, there was a dermal proliferation composed of epithelioid & spindled cells within a myxoid background. The epithelioid cells had round vesicular nuclei, small nucleoli & abundant cytoplasm, with focal intracytoplasmic vacuoles. Significant nuclear pleomorphism was not observed. Rare mitotic figures were noted, but atypical mitoses were not seen. Immunohistochemical studies showed that the cells were positive for EMA, D2-40, CD10, CD34 (focal), with retained INI1 & a low Ki-67 proliferation rate (<5%), while S100, SOX10, cytokeratin AE1/AE3, p63, desmin, ERG, Factor XIIIa, CD163, & CD99 were negative. Due to the unusual histopathological findings, tissue was sent for a comprehensive NGS Sarcoma Fusion Panel which revealed a PTEN::RNLS out of frame translocation. Additional copy number analysis using methylation array identified 10q amplification spanning the PTEN gene. The patient showed no evidence of local recurrence in 2-years of follow-up. PTEN::RNLS fusion has been previously described in bladder urothelial carcinomas & to the best of our knowledge, has not been reported in cutaneous/superficial soft tissue tumors. This fusion may result in tumor development through the loss the major protein functional domain in PTEN which is a tumor suppressor due to the frame-shifted ORF. Our report highlights potential novel gene rearrangement induced tumors related to disruption of tumor suppressor genes. It also expands the histopathological & clinical spectrum of tumors with PTEN::RNLS translocation beyond its known association with bladder urothelial carcinoma.