title: 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.
authors.affiliation: Department of Pathology, University General Hospital, Valencia, Spain. vicente.sabater@uv.es
authors.forename: Vicente
authors.initials: V
authors.lastname: Sabater Marco
authors.forename: Begoña
authors.initials: B
authors.lastname: Escutia Muñoz
authors.forename: Arturo
authors.initials: A
authors.lastname: Morera Faet
authors.forename: Manuel
authors.initials: M
authors.lastname: Mata Roig
authors.forename: Rafael
authors.initials: R
authors.lastname: Botella Estrada
mesh_terms: D019943:Amino Acid Substitution; D002648:Child; D003872:Dermatitis / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D020125:Mutation, Missense; D018332:Nevus, Epithelioid and Spindle Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000378:metabolism; D009418:S100 Proteins / Q000235:genetics / Q000378:metabolism; D012878:Skin Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology
chemical_list: D009418:S100 Proteins; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)