Merkel cell carcinoma of left ear and external auric canal

This code signifies a rare and aggressive neuroendocrine carcinoma originating from Merkel cells, specifically located on the left ear or within the external auditory canal. It presents as a rapidly growing, firm, often painless nodule, typically on sun-exposed skin.

Apply this code when documentation confirms a pathological diagnosis of Merkel cell carcinoma affecting the left ear or its external canal. This diagnosis is usually established via biopsy and immunohistochemical staining. Use this code for initial diagnosis, treatment planning, and follow-up care for this specific tumor site.

• Ensure the laterality (left ear) and specific anatomical site (external auricular canal) are clearly documented to support this precise code.
• Distinguish from other skin malignancies like squamous cell carcinoma or basal cell carcinoma, which have different ICD-10-CM codes.
• Always sequence this code as the primary diagnosis when it is the reason for the encounter, followed by any relevant secondary diagnoses such as metastatic disease.