Merkel cell carcinoma of the cheek: diagnosis in an elderly woman.

Editor,

Merkel cell carcinoma (MCC) is an uncommon primary neuroendocrine skin tumour. It is commonly seen in the elderly, on the sun exposed areas which can mimic benign or less malignant skin tumors. We report a case of Merkel cell carcinoma of cheek in an elderly woman which was initially treated as a boil. This highlights the importance of considering this tumour in the differential diagnosis of head and neck skin lesions as it is fatal if not diagnosed and treated early.

Case History

A 93 year old woman was referred, with a left cheek swelling, progressively increasing in size over a period of two to three months. An initial clinical diagnosis of boil necessitated the administration of two courses of antibiotics by her GP, before attending the general surgical clinic. On examination a single, firm, non-tender, purple pink swelling with superficial central ulceration was noted on the left cheek, measuring about 4×4cm size with well-defined margins and normal surrounding skin (Figure). The histology of a biopsy from an ulcer edge was consistent with Merkel cell carcinoma. Immunohistochemistry confirmed the diagnosis. Unfortunately this patient died two months after the diagosis.

Fig 1

Discussion

High index of suspicion is needed to diagnose some of the rare skin lesions. Merkel cell carcinoma of the skin is one of those uncommon, aggressive, neuroendocrine, cutaneous tumour most commonly found in head and neck region. It is a rare neuroendocrine tumour of the skin accounting for less than 1% of cutaneous malignancies, usually presents as red, purple or violaceous firm painless nodule or plaque. It is often mistaken for more common skin tumours because of its rarity.

Diagnosis can be made with histology alone and electron microscopy is encouraged as histologically it can resemble many other neoplastic processes. Immunohistochemistry is required for the definitive diagnosis of Merkel cell carcinoma. In our case malignant cells stained positive for CAM 5.2, CK-20 and chromogranin and negative for S100 and LCA (leukocyte common antigen).

Surgical treatment is the corner stone of the treatment. Wide local excision with a clearance margin of 3-5 cm is commonly recommended1–4. It is widely accepted that patients with regional node metastasis should undergo lymph node dissection. Adjuvant radiation therapy is generally recommended for primary site and lymph node basin in stage I and II disease. It may also be used as the only treatment for patients who are not fit for any surgical resection. Chemotherapy is generally reserved for the stage III disease. And no chemotherapeutic protocol has been able to achieve a significant increase in survival rate3

Conclusion

Some distinctive features of presentation are red, violaceous, intradermal nodule in sun exposed areas. High index of suspicion is needed at first presentation as it frequently proves lethal despite various multimodal therapies if not diagnosed early. It is clear from the available data that early diagnosis and wide local excision will prolong the survival.