A Unique Case of Squamous Cell Carcinoma Presenting Within a Lesion of Granuloma Annulare

Granuloma annulare (GA) is a common benign granulomatous inflammatory disorder of the dermis or subcutis with classic morphologic and histologic presentation. Common clinical subtypes of granuloma annulare include localized, generalized, subcutaneous, perforating, and patch types. A biopsy is critical in cases of granuloma annulare with atypical features. We present a case of a 58-year-old male who presented with an annular scaly erythematous plaque on the right dorsal hand. Shave biopsy demonstrated irregular nests of mildly atypical squamous epithelium present within the superficial dermis, with abundant histiocytes and multinucleated giant cells arranged in palisades peripherally. These findings were consistent with invasive well-differentiated squamous cell carcinoma (SCC) with surrounding granuloma annulare. This case highlights a unique presentation in which clinicopathologic correlation is critical prior to arriving at a correct diagnosis.