INTRODUCTION
Cancer is a leading cause of death worldwide, with deaths from cancer projected to continue rising in the next decade. Cutaneous metastases from visceral malignancies can be notoriously variable in their clinical presentation and may be the first sign of the primary internal cancer.1 Failure to recognize the etiology of the skin lesion may lead to delay in appropriate treatment and consequent morbidity and mortality.
CASE REPORT
A 50-year-old man with a history of metastatic lung adenocarcinoma was referred for evaluation of a nodule overlying his right mandible, which had been progressively enlarging for two weeks. The patient denied a preceding vesicle or pustule, prior trauma to the area, or a history of similar lesions. He had no personal history of skin cancer. The nodule was painless and non-pruritic and he denied any other skin lesions. The patient’s medical history was significant for a 30 pack-year smoking history, and prior radiation therapy and paclitaxel-carboplatin chemotherapy for lung adenocarcinoma. A staging CT scan completed on the day of referral showed interval improvement in the size of the patient’s lung mass but progressive retroperitoneal lymphadenopathy.
Skin examination revealed a fixed 2 cm erythematous non-fluctuant non-tender nodule located on the right mandible, lateral to the mental protuberance (Figure 1). No other cutaneous lesions were noted and no cervical or supraclavicular lymphadenopathy was appreciated. A 4-0 mm punch biopsy was obtained from the right chin. Histopathologic examination of the punch biopsy revealed a proliferation of atypical epidermal keratinocytes with irregular aggregates that infiltrated the reticular dermis (Figure 2). There was no connection to the overlying epidemis. The keratinocytes had hyperchromatic pleomorphic nuclei and eosinophilic cytoplasm. The neoplastic cells reacted for CK5/6, P63 and focally for EMA and CEA. There was no reactivity for CK7 or CK20. The diagnosis was therefore consistent with metastatic squamous cell carcinoma (SCC).
Subsequently, a CT-guided biopsy of a left retroperitoneal lymph node was conducted and notable for metastatic SCC, with tumor cells positive for P63 and CK5/6 and negative for NAPSIN-A, TTF-1, CK7, and CK20. Testicular ultrasound was normal and gastric biopsy was negative for dysplasia. The patient was started on gemcitabine-carboplatin chemotherapy by his oncologist and the chin nodule was resected by a head and neck surgeon. The patient died several months later.
DISCUSSION
Cutaneous metastases occur in 0.6%–10.4% of all patients with cancer and represent 2% of all skin tumors.1 The proportion of
