Pigmented squamous cell carcinoma of the cheek skin probably arising from solar keratosis

Abstract

We report a rare case of pigmented squamous cell carcinoma (SCC) of the cheek skin probably arising from solar keratosis. An 80-year-old man was referred to our clinic because of a black skin nodule in the right cheek. The nodular lesion was 1 cm in diameter, dome-shaped, hard, sharply demarcated, partially erosive and telangiectatic at the border. The lesion was completely excised under the clinical diagnosis of probable seborrheic keratosis. Microscopically, cutaneous horn and mildly atypical squamous epithelia suggestive of previous solar keratosis were present in the surface of the lesion. The lesion consisted of atypical squamous cells with keratinization and intercellular bridges, and it was regarded as SCC. The SCC cells were seen to invade lightly into the upper dermis, where lymphocytic infiltrations and melanophages were noted. Characteristically, heavy deposition of melanin pigment was recognized in the SCC cells as well as in proliferated dendritic and pigment blockade melanocytes that were scattered or colonized within the SCC cell nests. Masson-Fontana stain revealed numerous melanin granules in the SCC cells, as well as in dendritic and pigment blockade melanocytes. Immunohistochemically, the SCC cells were positive for cytokeratins and epithelial membrane antigen, and negative for S-100 protein and HMB45 antigen. Dendritic and pigment blockade melanocytes were negative for cytokeratins, epithelial membrane antigen, and HMB45 antigen, but positive for S-100 protein. The present case suggests that SCC cells of the skin may induce proliferation of melanocytes. The differential diagnosis and the histogenesis of pigmented SCC of the skin are discussed.

Pigmented Squamous Cell Carcinoma

“…9,10 Although pigmented squamous cell carcinomas (PSCC) have been reported in the cornea, conjunctiva, and oral mucosa, they are relatively rare in the skin, with only 17 reported cases, inclusive of the present one, in the English literature (Table 1). 1,[3][4][5]8,[12][13][14] The reported incidence of PSCC varies from 0.01% (5 cases of 46,791 invasive SCC examined) 8 to 7% 1 ; however, in the nonEnglish literature the incidence has been reported to be as high as 25%. 9,11 The difference in incidence may in part be due to the fact that the amount of pigment within the lesion is often sparse and may only be discernible by special techniques, or it may be race dependent.…”

“…The melanocytes in these lesions are cytologically benign, and it is hypothesized that their presence can be attributed to ''colonization'', rather than to a truly neoplastic process. [1][2][3][4][5][6][7] It is difficult to determine the actual incidence of this finding; because in general, benign neoplasms and non-melanocytic cutaneous malignancies are not reported to tumor registries. Moreover a pigmented modifier may not be incorporated into the coding system of many pathology reports for easy data retrieval.…”

An atypical pigmented lesion on the nose—Answer

“…PCSCC had been more often reported to occur in the oral mucosa and conjunctiva [3]. Pigmentation is probably due to cytokines secreted by tumoral cells that stimulate melanocytes to produce melanin [4]. In some cases, PCSCC may be the malignant progression of a pigmented actinic keratosis or a pigmented Bowen’s disease [4].…”

Spreading pigmented actinic keratosis: A review

“…33 Another case reported concomitant SPAK and pigmented squamous cell carcinoma on an 80-year-old patient's cheek. 34 …”