Track: Clinical Studies

Abstract:

Digital papillary adenocarcinoma (DPA) is a rare malignant sweat gland tumor affecting fingers and toes most commonly. HPV42 has become a desirable criterion for the diagnosis. No characteristic genetic alterations in DPA have been found except for BRAF V600E mutations in small case series and single case reports. The aim of this study was to add to the data on the prevalence of HPV42 detection and BRAF V600E mutational status in digital papillary adenocarcinoma.

Ethics approval was obtained, H&E-stained sections and immunohistochemistry for BRAFV, S100, SOX10, SMA, p63/p40, CK7, CK5/6, YAP1 and were reviewed, and low-risk HPV-ISH including HPV42 was performed. Clinical follow-up was obtained from patient records. Twenty-eight tumors were included and presented on the fingers (23), feet (4) and vulva (1) with a median size of 1.5 cm. The patient age ranged from 11 to 88 years (median: 49.5; M:F=3.7:1). Histopathologically, DPAs presented as multinodular, poorly- or well-circumscribed tumors in the dermis and subcutaneous tissue, composed of solid, cystic, and papillary growth patterns. Cytological atypia was mild to moderate. All tumors were positive for low-risk HPV-ISH. BRAFV immunohistochemistry was negative in all tumors. Two patients developed lung metastases, all other patients were alive without recurrences (median follow-up: 42.5 months, range 7-192 months).

This study does not support a pathogenic role of BRAF V600E mutation in DPA but confirms HPV42 infection in all tumors.

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Daniel Alt