Vulvar mastocytosis: atypical location

Mastocytosis represents a heterogeneous group of disorders characterized by excessive proliferation and accumulation of clonal (neoplastic) mast cells (MCs) in one or more organ systems. The differential diagnosis of mastocytosis is based on the evaluation of complaints, the presence of specific symptoms related to mast cell activation syndrome, and the assessment of symptom severity. In vulvar mastocytosis, there may be edema, hyperemia, and pain in the vulva associated with spontaneous or allergen-induced histamine release. Of importance is the detection of non-specific markers: blood tryptase and products of histamine metabolism in the urine, which may be increased either due to elevated levels of basophils, or because of their pathologic activation. The mandatory diagnostic method is biopsy and immunohistochemistry for CD117, CD25, CD2, CD30 markers, tryptase levels in a sample, and determination of specific, more pronounced basophil staining. In recent years, the detection of KIT D816V mutation by sensitive allele-specific quantitative PCR has been a reliable screening method. This clinical case demonstrates the relevance of the problem of mastocytosis and its differential diagnosis in medical practice, since this disease is quite rare and causes diagnostic difficulties. Key words: mastocytosis, cutaneous mastocytosis, vulvar neoplasms, c-KIT