Solitary hard plaque on scalp with pustules: An unusual case of secondary osteoma cutis

Suman Patra, Snehal Agarwal, Vinod K Sharma, M Ramam

 Department of Dermatology and Venereology, All India Institute of Medical Sciences, New Delhi, India

Correspondence Address:
Vinod K Sharma
Department of Dermatology and Venereology, Room No. 4070, 4th Floor, Teaching Block, All India Institute of Medical Sciences, New Delhi
India

A 42-year-old man presented with a gradually progressive asymptomatic irregular firm-to-hard plaque of 3 cm × 4.5 cm size on the right parietal scalp since last 15 years [Figure - 1]. He had recurrent scalp folliculitis and there were pustules on the plaque with scarring alopecia. Histopathology of the plaque revealed multiple small, medium and large nodules of calcification with eosinophilic osteoid material in varying proportion around it. In addition, there was moderately dense infiltrate of plasma cells, lymphocytes, histiocytes and small collection of neutrophils accompanied by fibrosis. Plain X-ray of the scalp showed extracranial calcification corresponding to the plaque. His serum calcium, phosphate, parathyroid hormone and vitamin D3 were within normal limit. Overall, a diagnosis of osteoma cutis possibly secondary to folliculitis was made. The lesion was completely excised.

Figure 1: Irregular-shaped plaque on right parietal scalp with overlying pustules

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