Solitary mastocytoma presenting in an adult: report and literature review of adult-onset solitary cutaneous mastocytoma with recommendations for evaluation and treatment.

BACKGROUND: Mastocytosis is either cutaneous (with skin-limited proliferation of mast cells) or systemic (with mast cells in extracutaneous sites). The onset of solitary mastocytoma in an adult is rare.

PURPOSE: A woman with the new onset of solitary mastocytoma is described. The clinical features of patients with adult-onset solitary mastocytoma are summarized. Recommendations for the evaluation and treatment of individuals with adult-onset solitary mastocytoma are proposed.

METHODS: PubMed was searched with the key words: adult, CD2, CD25, cell, cutaneous, disease, KIT, KIT D816V, mast, mastocytoma, mutation, pigmentosa, solitary, tryptase, and urticarial. The papers generated by the search, and their references, were reviewed.

RESULTS: A 38-year-old Taiwanese woman presented with an asymptomatic brown patch, which morphologically mimicked a dysplastic nevus, on her right abdomen; biopsy demonstrated a solitary mastocytoma. Comprehensive evaluation (including serologic and bone marrow examination) excluded systemic mastocytosis and her residual mastocytoma is being monitored. Adult-onset solitary mastocytoma has been described in 16 patients. Lesions were either on the head and neck (5/14), torso (5/14) or extremities (4/14). Urtication following lesion rubbing was noted in 79% (11/14) of patients. Excision of the mastocytoma [75% (9/12)] was the most common treatment. Other management approaches included corticosteroids (topical or intralesional), antihistamines (systemic) or observation. Systemic symptoms were noted in 5 patients: flushing (3 women) and pruritus (3 women); gastrointestinal symptoms and headaches, flushing and/or anaphylaxis were each noted in one woman. None of the patients with adult-onset solitary mastocytoma had systemic mastocytosis; however, only 3 women were evaluated for systemic mastocytosis.

CONCLUSIONS: Systemic mastocytosis is common in adults with new onset cutaneous mastocytosis. Therefore, a conservative work up for new onset solitary mastocytosis in adults is proposed to include complete blood cell counts, serum chemistries (including liver function tests), and serum tryptase level and bone marrow biopsy to evaluate for mast cell clusters, morphology and immunophenotype and KIT gene mutation in codon 816. Similar serologic testing should be considered annually for adult-onset solitary mastocytosis patients without systemic disease.