[Diffuse cutaneous mastocytosis. Presentation of 3 cases and therapeutic management review]

Localized Grain-Leather Plaque in Urticaria Pigmentosa - An Unusual Coexistence of Dual Morphology

Urticaria pigmentosa (UP), the most common variant of cutaneous mastocytosis (CM), is characterized by hyperpigmented, brownish macules and patches, with positive Darier's sign. Diffuse cutaneous mastocytosis (DCM), is a rare variant of CM, characterized by diffuse infiltration of the skin by mast cells (MCs), resulting in a typical grain-leather appearance. Blistering is commonly seen in infants with CM but it is not specific for any variant of CM. Herein, we report a case of a 5-month-old male infant who presented with recurrent bullous lesions and hyperpigmented, brownish patches with intervening normal skin suggestive of UP, as well as a single, localized plaque with grain-leather appearance, thereby exhibiting an interesting dual morphology.

Systemic mastocytosis with KIT V560G mutation presenting as recurrent episodes of vascular collapse: response to disodium cromoglycate and disease outcome

Background

Mastocytosis are rare diseases characterized by an accumulation of clonal mast cells (MCs) in one or multiple organs or tissues. Patients with systemic mastocytosis (SM), whose MCs frequently arbor the activating D816V KIT mutation, may have indolent to aggressive diseases, and they may experience MC mediator related symptoms. Indolent SM with recurrent anaphylaxis or vascular collapse in the absence of skin lesions, ISMs(−), is a specific subtype indolent SM (ISM), and this clonal MC activation disorder represents a significant fraction of all MC activation syndromes. The V560G KIT mutation is extremely rare in patients with SM and its biological and prognostic impact remains unknown.

Case presentation

A 15-year old boy was referred to our hospital because of repeated episodes of flushing, hypotension and syncope since the age of 3-years, preceded by skin lesions compatible with mastocytosis on histopathology that had disappeared in the late-early childhood. Diagnosis of ISM, more precisely the ISMs(−) variant, was confirmed based on the clinical manifestations together with increased baseline serum tryptase levels and the presence of morphologically atypical, mature appearing (CD117+high, FcεRI+) phenotypically aberrant (CD2+, CD25+) MCs, expressing activation-associated markers (CD63, CD69), in the bone marrow. Molecular genetic studies revealed the presence of the KIT V560G mutation in bone marrow MCs, but not in other bone marrow cells, whereas the screening for mutations in codon 816 of KIT was negative. The patient was treated with oral disodium cromoglycate and the disease had a favorable outcome after an eleven-year follow-up period, during which progressively lower serum tryptase levels together with the fully disappearance of all clinical manifestations was observed.

Conclusions

To the best of our knowledge this first report of a patient with ISM, whose bone marrow MCs carry the KIT V560G activating mutation, manifesting as recurrent spontaneous episodes of flushing and vascular collapse in the absence of skin lesions at the time of diagnosis, in whom disodium cromoglycate had led to long term clinical remission.