Track: Case Reports

Topic: Neoplasia,Carcinogensis,Tumor Biology

Abstract:

A 70-year-old male, Liver transplant patient presented with a papular lesion on the right eyebrow. Biopsy showed dermal neoplasm, composed of spindle cells with pleomorphic nuclei, multinucleated cells, and mitosis(2/mm²) on a background of solar elastosis. Immunohistochemistry was negative for all lineage markers including AE1/AE3, CK5/6, p40, S100, SOX10, CD31 and desmin, leading to a diagnosis of AFX. Following excision with negative margins, the lesion recurred four years later. Subsequent metastases ensued to the cheek, buttock, abdominal wall, and lung. Biopsies from all sites demonstrated morphology like that in the original SLTS, prompting a diagnosis of PDS. Molecular studies revealed PIK3CA, TERT, CDKN2A variants, and truncating mutations in TP53, TSC2, STAG2, and PPM1D in the buttock and oral biopsies, confirming the unusual pattern of metastasis.

In a clinicopathologic comparison between SLTS and spindle cell carcinoma of the skin (SCCS) — described by Harry Evans (1980) — depth of invasion was the key predictor of outcome in both tumor types and remains the most potent morphologic prognostic indicator in SLTS.

The advent of NGS has provided additional insight into molecular aspects of SLTS; however, host factors, such as immunosuppression and history of solar and other radiation also play an important role in clinical outcomes and may be underrecognized. Evolving clinicopathologic and molecular data underscore a need for structured reporting protocols similar to those in existence for SCCS. Incorporation of clinical, morphologic, and molecular data into a risk stratification protocol may have critical managerial importance and open new pathways for optimizing patient care.

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Matthew Leong, MD