The Journal of Laryngology and Otology December 1997, Vol. Ill, pp. 1195-1198 Pathology in Focus Merkel cell carcinoma of the pinna B. SKIA, M . S C , A. BIBAS, F.R.C.S.I., S. A. HICKEY, M.A., F.R.C.S., N. G. RYLEY, M.R.C.PATH. Abstract Merkel cell carcinoma is an increasingly recognized tumour of the skin. The commonest presentation is the head and neck region. Only three cases of this rare tumour have been reported on the pinna. A further such case is presented here. Key words: Head and neck neoplasms; Carcinoma, Merkel cell; Skin Introduction Merkel cell carcinoma, also known as neuroendocrine carcinoma of the skin is a rare cutaneous tumour. It was first described in 1972 by Toker as a trabecular carcinoma of the skin (Toker, 1972). Since then three variants have been suggested: the trabecular, the intermediate and the small cell type (Gould et al., 1985). Toker in his original article suggested that the tumour originated from epithelial structures in the dermis, e.g., sweat glands. Later the presence of neurone-specific enolase, a marker of cells of neuroendocrine origin was noted in these tumours. Since the Merkel cell is the only cell in the skin that contains neuroendocrine granules, it has been suggested as the possible cell of origin of this tumour; hence the name Merkel cell carcinoma (Pitale et al., 1992). The origin of the Merkel cell itself is still controversial, with evidence suggesting origin from both the neural crest and a transitional cell in the basal layer of the epidermis. The understanding of this disease is based on collected case reports and therefore for further understanding of the tumour's behaviour it seems important to describe every case, as was stressed by other authors (Raaf et al., 1986; Marks et al., 1990). and apoptotic cells (Figure 2). The immunohistochemical profile was of strong cytoplasmic staining with MNF 116 (a broad spectrum anticytokeratin 5, 6, 8, 17 and 19) and the more specific anti-cytokeratin 20. These showed the characteristic 'dot' positivity (Figure 3). Neuron-specific enolase showed strong diffuse cytoplasmic staining, but chromogranin (a neuroendocrine marker) was only focally and weakly positive. Other antibody labels (epithelial markers BerEP4 and CEA, general lymphoid marker CD45, and the neural crest derivative marker S100) were negative. The excision biopsy of the primary lesion was followed by a wide excision of the satellite nodules and reconstruction with a locoregional rotation flap. The pre-operative investigations revealed microcytic anaemia and further medical investigation with upper gastrointestinal endoscopy revealed an asymptomatic tumour of the body of the stomach extending to the cardia and invading the lower oesophagus. Association with the lesion of the pinna was excluded by histochemical staining, which confirmed a second primary poorly-differentiated carcinoma. The gastric tumour was deemed to be inoper- able. His condition rapidly deteriorated and he died two months later. Case report An 84-year-old gentleman was referred by his general practitioner to the ENT Department of Torbay Hospital with a two-month history of a left pinna lesion. On examination there was a 3 x 2 cm ulcerated lesion on the cranial aspect of the left pinna and three satellite nodules in the ipsilateral post-auricular region. There was no associated cervical lymphadenopathy and the rest of the ENT examination was normal. An excision biopsy of the primary lesion, under local anaesthesia, revealed a neuroendocrine carcinoma of the skin (Merkel cell carcinoma). It showed the characteristic histological features with a deeply invasive (Figure 1) and focally necrotic tumour composed of sheets of monotonous cells with very little cytoplasm, displaying frequent mitoses Discussion The most common site of presentation of Merkel cell carcinoma is the head and neck (50 per cent), followed by the extremities (35 per cent) and other areas (15 per cent) (Trimas et al, 1992). It is important that the otolaryngol- ogist is aware of this carcinoma when faced with cutaneous lesions of the head and neck region. The tumour manifests typically in the elderly as a slowly enlarging pink plaque or nodular subcutaneous lesion (Hitchcock et al, 1988). It has a typical bluish-red appearance, with the overlying skin intact, shiny and rarely ulcerated (Domarus et al., 1985). It follows an aggressive clinical course with a propensity for local recurrence, lymph node involvement and distant metas- tasis (O'Brien et al., 1987; Canales et al., 1992). From the Departments of Otolaryngology and Pathology*, Torbay Hospital, Lawes Bridge, Torquay, UK. Accepted for publication: 12 September 1997. 1195