Nodule on upper back
How to cite this article: Narayanan A, Thappa DM, Rajesh NG. Nodule on upper back. Cosmoderma 2021;1:7.
A 50-year-old male patient presented to us with a well-defined, skin-coloured, painless nodule over the left scapular area which was gradually increasing in size for the last 1 year. Differential diagnosis of dermatofibroma, neurofibroma, lipoma, leiomyoma, and benign appendageal tumors were considered. The nodule was excised and histopathological examination of the sections revealed branching nests of basaloid cells in a cribriform pattern admixed with keratin horn cysts [Figure 1(a–b)]. These basaloid cells have a round-to-oval hyperchromatic nuclei and scant cytoplasm. There was no atypia, mitosis, or necrosis. Multiple cleft-like spaces were seen within the tumour stroma and in the surrounding tissue [Figure 2(a–c)]. A diagnosis of trichoblastoma was made based on the histopathological findings. Trichoblastoma is a rare tumor of follicular bulbar differentiation presenting as a skin-coloured, papule or nodule over the face or upper trunk. On histopathology, it can be differentiated from basal cell carcinoma (BCC) by the presence of stromal cleft and papillary mesenchymal bodies. In addition, absence of epithelial stromal cleft, mitosis, atypia, and necrosis favors a diagnosis of trichoblastoma over BCC. It is a benign condition treated with excision, laser, or electrosurgical destruction.