Subcutaneous metastasis of a pulmonary carcinoid tumor: A case report

Rationale: Carcinoid tumors are derived from neuroendocrine cells and are most frequently found in the gastrointestinal tract and bronchopulmonary system. They are generally characterized by an indolent clinical course but may in some instances spread to regional lymph nodes or to distant sites. Subcutaneous metastases of carcinoid tumors are extremely rare; there are only few cases reported in the literature and the site of the primary tumor was mainly the gastrointestinal tract. Also, the diagnosis of this type of lesions many years after the surgical resection of the pulmonary carcinoid (PC) could be a challenge for clinicians. Patient concerns: A nonsmoker woman diagnosed with a atypical carcinoid stage IA2 maintained follow-up at our institution. Seven years later she incidentally detected a subcutaneous nodular lesion in the lumbar region. Diagnoses: A positron emission tomography-computed tomography (PET/CT) was performed and showed pathological uptake of the refered lesion. An excisional biopsy was performed and with the support of immunohistochemistry the diagnosis of a subcutaneous metastasis from a pulmonary atypical carcinoid was made. Interventions: The patient initiated chemotherapy with carboplatin plus etoposide and complied 4 cycles of treatment. Outcomes: She maintained tight follow-up at our center and for 12 months there were no signs of relapse. Lessons: This extremely rare case highlights the difficulties in the differential diagnosis and the importance of diagnostic tests as PET/CT and immunohistochemistry in the establishment of a diagnosis. Physicians should be aware of signs of skin metastasis from lung malignancies even if the prognosis is good or many years have passed since the surgical resection.