Perianal mass as the debut of metastatic pulmonary neoplasia

A 56-year-old male smoker presented to the Emergency Department with a painful mass in the left ischiorectal fossa, which had been present for 2 months without any other symptoms. On examination, a hard, violet-colored mass was observed, with an ulcerated central area. Blood tests were normal, and the abdominal-pelvic CT scan showed multiple hypervascular intra-abdominal masses and soft tissue lesions. A biopsy was performed, revealing a poorly differentiated metastatic carcinoma. Further investigation with a brain MRI was normal, and a chest CT showed pathological lymphadenopathy and a cavitary pulmonary mass suggestive of a primary tumor.