Aggressive papillary adenocarcinoma on atypical localization: A unique case report

INTRODUCTION: Aggressive digital papillary adenocarcinoma (ADPA) is a rare sweat gland tumor that is found on the fingers, toes, and the digits. To date, <100 cases have been reported in the literature. Apart from 1 case reported in the thigh, all of them were on digital or nondigital acral skin. CASE PRESENTATION: A 67-year-old Caucasian woman was admitted to the hospital due to a mass on the scalp. This lesion was present for almost a year. It was a semimobile cyctic mass that elevated the scalp. There was no change in the skin color. Its dimensions were 1.5 × 1 × 0.6 cm. The laboratory, clinic, and radiologic findings (head x-ray) of the patient were normal. It was evaluated as a benign lesion such as lipoma or epidermal cyst by a surgeon due to a small semimobile mass and no erosion of the skull. It was excised by a local surgery excision. The result of the pathologic examination was aggressive papillary adenocarcinoma. This diagnosis is synonymous with ADPA. CONCLUSION: In our case, localization was scalp. This localization is the first for this tumor in the literature. In addition, another atypical localization of this tumor (ADPA) is thigh in the literature. This case was presented due to both the rare and atypical localizations. That is why, in our opinion, revision of “digital” term in ADPA is necessary due to seem in atypical localizations like thigh and scalp.