Acrometastasis of the Finger Revealing Occult Pulmonary Squamous Cell Carcinoma in a Patient with Papillary Urothelial Carcinoma: A Rare Case Report

Acrometastases are rare and may exceptionally reveal an occult carcinoma. The prognosis is often poor. Imaging and immunohistochemical studies are essential to determine the primary origin and guide treatment. Bone acrometastasis of the finger as the initial manifestation of an occult primary malignancy is exceptionally reported in the literature. Diagnostic delays and even misdiagnoses are frequent. We report a case of acrometastasis of the first phalanx of the left index finger revealing a pulmonary squamous cell carcinoma in a 61-year-old, chronic smoker followed for low-grade papillary urothelial carcinoma.The clinical history dated back three months, marked by the appearance of a painful swelling of the left index finger. Biopsy of the mass of the first phalanx revealed a tumor proliferation. Immunohistochemistry was consistent with a poorly differentiated, non-keratinizing, infiltrating pulmonary squamous cell carcinoma expressing CK and P63.The interest of our study lies in reporting a rare case of acrometastasis revealing pulmonary squamous cell carcinoma.