| A rare slowly progressive form of systemic mastocytosis (SM) with characteristics of gradual accumulation of neoplastic mast cells in the visceral organs. Patients typically present with splenomegaly, hypercellular marrow and in most cases urticaria pigmentosa-like skin lesions. Although the etiology is not fully understood, an activating mutation of KIT, usually KIT D816V, is found in the mast cells of virtually all cases. This mutation probably accounts for the abnormal accumulation of mast cells in organs/tissues. |
