Merkel Cell Carcinoma of the Pinna

Abstract

A 36-year-year old man had a 6-month history of a progressively increasing painless swelling of the left pinna associated with a swelling in the left upper neck. Physical examination revealed a 3 × 5 cm exophytic 1 obulated mass on the lower half of the lateral surface of the left pinna (Fig. 1). The overlying skin color varied from violet to dark brown with ulceration in places. Examination of the neck revealed 2 × 2 cm level II node on the left side of the neck. Fine-needle aspiration (FNA) of the cervical lymph node showed numerous small and anaplastic malignant cells. Incisional biopsy of the pinna swelling showed undifferentiated cells arranged in sheets and clusters. The cells had large nuclei with stippled chromatin and showed frequent mitoses. Immunohistochemistry showed positive staining for cytokeratin, neuron-specific enolase, chromogranin, and synaptophysin. On the basis of these findings, the diagnosis was Merkel cell carcinoma (MCC). He underwent wide local excision of the tumor and radical neck dissection followed by 55 Gy of external radiotherapy. Seven months later, he noticed swellings on the right side of the neck. A CT scan showed multiple lymph nodes on the right side of the neck and retropharyngeal lymph nodes. FNA of the cervical lymph nodes showed features similar to those of an FNA of the left neck nodes done previously. The patient received chemotherapy for palliation. Six months later metastases developed in the superior mediastinal and intraabdominal lymph nodes, and the patient died.

DISCUSSION

MCC is a rare skin tumor. It was first described as trabecular carcinoma by Toker 1 in 1972. The presence of neurosecretory granules within the tumor cells suggested that the neoplasm might originate from the Merkel cells, and accordingly, the term Merkel cell tumour was introduced. 2 However, doubt remains to the exact histogenesis of this carcinoma.

The head and neck region is the most frequently (>50%) encountered primary site, followed by the extremities and the trunk. Head and neck MCC has an almost even gender distribution, with average presentation age of 72.1 years and an average tumor size of 2.0 cm. 3 The tumor is usually described as being red to violet, painless, nodular, and firm. High rates of local recurrence (37%), regional metastasis (48%), and distant disease (28%) have been described. 3 The ear is infrequently (7%) involved. 3

The differential diagnosis includes undifferentiated squamous cell carcinoma, lymphoma, malignant melanoma, neuroblastoma, poorly differentiated metastatic carcinoma, sweat gland carcinoma, and carcinoid tumors. 4 The diagnosis of MCC is usually aided by multiple immunohistochemical stainings, which reveal tumor cells with strong positive staining for cytokeratin and neuron-specific enolase. 4

Although total surgical extirpation with clear margins is the treatment goal, other treatment modalities, including radiation therapy, chemotherapy, and hyperthermia, are often added. 3 However, MCC remains a vicious form of skin carcinoma with a propensity for rapid local and regional recurrence followed by widespread metastases and a grave outcome.

Figure 1

MCC arising from the lower half of the lateral surface of the left pinna.

References

Toker

Trabecular carcinoma of the skin. Arch Dermatol 1972;105:107–10.

Rice

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Thompson

Merkel cell tumor of the head and neck: five new cases with literature review. Arch Otolaryngol Head Neck Surg 1993;119:782–6.

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Merkel cell carcinoma of the pinna. J Laryngol Otol 1988;102:608–11.

De Wolf-Peeters

Marien

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A cutaneous APUDoma or Merkel cell tumor? A morphologically recognizable tumor with a biological and histological malignant aspect in contrast with its clinical behavior. Cancer 1980;46:1810–6.