The New Italian Mastocytosis Registry.

Mastocytosis is a rare disease characterized by an abnormal proliferation and accumulation of mast cells (MC) in several organs and tissues such as skin, bone marrow, liver, gastrointestinal tract and lymphnodes. The reported prevalence of mastocytosis (cutaneous or systemic) is lower than 1/50,000. Mastocytosis encompasses a wide range of clinical entities, extremely heterogeneous for symptoms, clinical course and prognosis. The heterogeneity and the complexity of its clinical signs lead to the definition of mastocytosis as a multidisciplinary pathology, involving different specialists such as hematologists, internists, dermatologists, immunologists and pediatricians. Mastocytosis is a MC clonal disease associated to a somatic mutation (D816V) of the proto-oncogene c-kit (KIT), which codifies for the stem cell factor (SCF) receptor. SFC is the main factor stimulating the proliferation, chemotaxis and activation of human mast cells. Different KIT mutations have been found in 15% of patients. Clinical signs and symptoms of mastocytosis mainly depend on the liberation of chemical mediators produced by the mast cells, on the tissue infiltration of the mast cells and on other associated hematological diseases. Aim of the Registry: promoting studies on mastocytosis in Italy aimed at investigating the epidemiology of the disease, its prognostic factors and health technology assessment (HTA) aspects associated to the management of a rare “orphan” disease.

The Italian Mastocytosis Registry was constituted in 2009, with the aim of promoting communication between specialists and collecting data about patients diagnosed with mastocytosis at a national level. Anagraphical, anamnestic, clinical, biological, treatment and follow-up data of patients with mastocytosis are being routinely collected in 15 Italian centers after written informed consent. An on-line database (www.registroitalianomastocitosi.it) has been set up for this purpose. The collected data will allow specialists to:

1. estimate the prevalence and the incidence of mastocytosis in Italy;

2. describe the natural history of the disease, mainly focusing on the evolution from cutaneous to systemic mastocytosis;

3. identify relevant prognostic factors for systemic mastocytosis;

4. provide the rationale for treatment development and testing.

At present, data on 175 patients have been collected. Seventy-nine (45%) have been diagnosed with systemic mastocytosis and 40 (50%) of them progressed from a cutaneous disease. Ninety-four (54%) are females; 81 (46%) are males. Among 49 patients for whom data on familiarity were available, 12 (24%) reported familiar cases of autoimmune diseases (n=3), allergies (n=5) or interestingly mastocytosis (n=4). Sixty-one (35%) patients reported allergies. Of 121 reported lines of therapy, 37 (31%) were described as not specified anti chemical mediators, 51 (42%) anti-H1, 21 (17%) anti-H2, 30 (25%) corticosteroids, 22 (18%) phototherapy, 7 (6%) alpha-interpheron, 8 (7%) chemotherapy and 13 (11%) tyrosine-kinase inhibitors (total exceeds 100% because multiple choice is allowed). As to the histological findings, 82 (47%) patients have data on bone marrow biopsy: 48 (59%) had a positive finding, with a median mast cells infiltrate of 30% (range 3–90%). Among 43 patients tested for tryptase serum level, 41 (95%) had levels above normal values (12.5 ng/ml).

This is the first spontaneous observational study on mastocytosis in Italy. The on-line database is a useful tool for data collection at a national level. The Registry is an opportunity to carry out epidemiological studies aimed at estimating occurrence and geographical distribution of the disease. It will also allow specialists to investigate possible prognostic factors and provide a starting point for the research into ad hoc therapies and HTA studies. It will hopefully provide a link with other international registries to improve understanding of this disease. Last but not least, the Italian Registry may support a National Government policy to provide assistance by the Public Health System to patients with mastocytosis.

No relevant conflicts of interest to declare.