Giant metastatic Merkel cell carcinoma.

Area of Science:

• Oncology
• Dermatology
• Pathology

Background:

• A 68-year-old male presented with a rapidly growing, asymptomatic left mid-back mass.
• Patient history included significant weight loss and smoking. He also had basal cell carcinomas and lymphadenopathy.

Observation:

• A fungating, 11-cm red tumor with a 23-cm underlying extension was noted on the left mid-back.
• Distinct red dermal nodules in a dermatomal distribution and ulcerated nodules were present.
• Massive, fixed lymphadenopathy was found in the left groin.

Findings:

• Biopsy revealed a dense infiltrate of small, round hyperchromatic blue cells.
• Tumor cells stained positive for CD 56 and pancytokeratin in a perinuclear dot pattern.
• Immunohistochemistry was negative for CK20, TTF, CK7, and LCA.

Implications:

• The findings suggest a rare diagnosis of neuroendocrine carcinoma.
• This case highlights the importance of thorough histopathological examination for diagnosing unusual skin tumors.
• Further research into the pathogenesis and treatment of such rare neuroendocrine skin cancers is warranted.