Background Diffuse cutaneous mastocytosis (DCM) is an extremely rare disease characterized by mast cell (MCs) infiltration of the entire skin. Little is known about the natural course of DCM.
Objectives We decided to characterize clinical manifestations, the frequency of MCs mediator-related symptoms and anaphylaxis, risk of systemic mastocytosis (SM) and prognosis, based on 10 cases of DCM, the largest series published to date.
Methods Diffuse cutaneous mastocytosis, DCM was confirmed by histopathological examination of skin samples in all cases. SCORing Mastocytosis (SCORMA) Index was used to assess the intensity of DCM. The analysis of clinical symptoms and laboratory tests, including serum tryptase levels was performed. Bone marrow biopsy was done only in selected cases.
Results Large haemorrhagic bullous variant of DCM (five cases) and infiltrative small vesicular variant (five cases) were identified. The skin symptoms appeared in age-dependent manner; blistering predominated in infancy, whereas grain-leather appearance of the skin and pseudoxanthomatous presentation developed with time. SM was not recognized in any of the patients. Mast cell mediator-related symptoms were present in all cases. Anaphylactic shock occurred in three patients. Follow-up performed in seven cases revealed slight improvement of skin symptoms, reflected by decrease of SCORMA Index in all of them. Serum tryptase levels declined with time in six cases.
Conclusions Diffuse cutaneous mastocytosis, DCM is a heterogeneous, severe, cutaneous disease, associated with mediator-related symptoms and risk of anaphylactic shock. Although our results suggest generally favourable prognosis, the review of the literature indicate that SM may occur. Therefore, more guarded prognosis should be given in DCM patients.