Integrated Clinicopathologic and Genetic Characterization of Renal TFE3-Rearranged PEComa with Melanin Pigmentation: A Case Series and Comprehensive Literature Review.
Zidi Zhou, Ting Lei, Yongqiang Shi et al.
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Case in brief
Three patients had renal masses detected on imaging; ultrasound showed well-circumscribed echogenic lesions. Histology demonstrated epithelioid tumors arranged in nests, sheets, or acini, with variable melanin pigmentation and a fibrovascular network. Tumor cells expressed TFE3 and HMB45 but lacked Melan-A, PAX8, and several other tested markers. Next-generation sequencing identified an SFPQ::TFE3 fusion in all three tumors, alongside reported missense mutations. All patients survived without recurrence or metastasis; the authors note that patients with kidney-confined tumors generally had good outcomes after complete surgical resection.
What made this case unusual
The tumors combined TFE3 rearrangement with melanin pigmentation, and were HMB45-positive but Melan-A-negative. One patient’s tumor also showed marked atypia, necrosis, dystrophic calcification, and atypical mitotic figures.
Diagnostic / clinical pearl
In a pigmented renal epithelioid tumor, the combination of TFE3 and HMB45 positivity with absent PAX8 and an SFPQ::TFE3 fusion supports renal TFE3-rearranged PEComa; distinguish it from Xp11 translocation renal cell carcinoma and conventional PEComa.
Why it matters
The report highlights a diagnostic overlap with renal cell carcinoma and conventional PEComa, making integrated morphology, immunophenotyping, and molecular findings relevant to classification.