Pseudogranulomatous Spitz nevus: a variant of Spitz nevus with heavy inflammatory infiltrate mimicking a granulomatous dermatitis

Abstract

Spitz nevus is a benign melanocytic proliferation that shows relatively characteristic clinicopathologic features. Despite this, Spitz nevus is clinically confused with many other lesions, and histopathologically it is sometimes difficult to distinguish it from melanoma. However, Spitz nevus rarely causes differential diagnostic problems with granulomatous dermatitis. This article describes an 8-year-old girl who presented with a nodule on her right arm, a clinical appearance of a pyogenic granuloma. Histopathologically, there was a dermal lesion composed of aggregates of large epithelioid cells surrounded by a heavy inflammatory infiltrate, mimicking a sarcoid-like granulomatous dermatitis. Immunohistochemistry showed epithelioid cells with strong nuclear and cytoplasmic staining with S-100 protein, thus establishing the diagnosis of a melanocytic tumor. The heavy T-cell lymphocytic infiltrate that accompanies the large epithelioid cells caused its granulomatous appearance. Molecular assessment showed H27H mutation in the HRAS gene. We suggest the term 'pseudogranulomatous' for this variant of Spitz nevus because it indicates that the lesion is not authentically granulomatous and simply mimics a granulomatous dermatitis.

The Spectrum of Spitz Melanocytic Lesions: From Morphologic Diagnosis to Molecular Classification

“…Pseudogranulomatous SN is characterized by a dense lymphocytic infiltrate surrounding nests of epithelial melanocytes located at the dermal-epidermal junction ( 6 , 36 , 168 ). The epidermal hyperplasia characteristic of SN is often accompanied with collarette ( 6 , 168 ).…”

“…Pseudogranulomatous SN is characterized by a dense lymphocytic infiltrate surrounding nests of epithelial melanocytes located at the dermal-epidermal junction ( 6 , 36 , 168 ). The epidermal hyperplasia characteristic of SN is often accompanied with collarette ( 6 , 168 ). Pyogenic granuloma is high on the differential for these lesions and clinically, they present as red, soft, sessile papules in young patients ( 168 ).…”

“…The epidermal hyperplasia characteristic of SN is often accompanied with collarette ( 6 , 168 ). Pyogenic granuloma is high on the differential for these lesions and clinically, they present as red, soft, sessile papules in young patients ( 168 ). Pseudogranulomatous SN stain positive for S-100 and HMB-45 and CD45 and CD3 can be detected in the lymphocytic infiltrate ( 168 ).…”

The stars within the melanocytic garden: unusual variants of Spitz naevi

“…However, Spitz naevi may present a wide spectrum of morphologies. Histopathologically, many variants, including desmoplastic, angiomatoid, verrucous/polypoid, plexiform, pagetoid, halo, myxoid, granulomatous and tubular Spitz naevi have been described . Clinical and dermoscopic features of these unusual variants of Spitz naevi have been reported only rarely.…”

Malignant melanoma in situ associated with underlying sarcoidal granuloma: A histopathological mimicker of invasive epithelioid melanoma cells

“…There are a few case reports of melanoma histologically showing giant cell cytomorphology, in primary 2 or metastatic 3 lesions. Moreover, one report described a case of Spitz nevus with markedly epithelioid cells mimicking granulomatous inflammation 4 . Thus, the granulomatous infiltrate seen in the current case raised the diagnostic issue of whether it was true granulomatous infiltrate or invasive melanoma.…”