Details
Excisional biopsy, soft tissue (right thumb).
Papillary digital adenocarcinoma (PDEA) occurs as a solitary painless mass, almost exclusively on the fingers, toes and adjacent parts of the palms and soles. Most tumours are nodular growths, less than 2cm in diameter. Over 90% are grossly cystic.
This case exhibits papillary digital adenocarcinoma of the eccrine sweat glands. This is a malignant adnexal tumour. The excisional specimen reveals subcutaneous fibroadipose tissue containing a well-circusmcribed, central cystic lesion with associated scarring and hemorrhagic changes. The cyst appears to be surrounded by a dense fibrous capsule and its contents include a complex papillary epithelial proliferation with evident glandular (eccrine) differentiation. Lesional cells show mild cytologic atypia and scattered mitotic activity (approx. 7 per 10hpf). There is no geographic tumoural necrosis or infiltrative growth.
PDEA can be a challenging and under-recognized entity, often mistaken for benign adnexal tumour, but shows aggressive metastatic/malignant potential. Given this, a correct diagnosis is crucial.