Childhood mastocytosis: results of a single center

Childhood Solitary Cutaneous Mastocytoma: Clinical Manifestations, Diagnosis, Evaluation, and Management

BACKGROUND

The diagnosis of solitary cutaneous mastocytoma is mainly clinical, based on lesion morphology, the presence of a positive Darier sign, and the absence of systemic involvement. Knowledge of this condition is important so that an accurate diagnosis can be made.

OBJECTIVE

To familiarize physicians with the clinical manifestations, diagnosis, evaluation, and management of a solitary cutaneous mastocytoma.

METHODS

A PubMed search was completed in Clinical Queries using the key term "solitary cutaneous mastocytoma". The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews. Only papers published in English language were included. The information retrieved from the above search was used in the compilation of the present article.

RESULTS

Typically, a solitary cutaneous mastocytoma presents as an indurated, erythematous, yellow- brown or reddish-brown macule, papule, plaque or nodule, usually measuring up to 5 cm in diameter. The lesion often has a peau d'orange appearance and a leathery or rubbery consistency. A solitary cutaneous mastocytoma may urticate spontaneously or when stroked or rubbed (Darier sign). Organomegaly and lymphadenopathy are characteristically absent. The majority of patients with skin lesions that erupt within the first two years of life have spontaneous resolution of the lesions before puberty. Treatment is mainly symptomatic. Reassurance and avoidance of triggering factors suffice in most cases.

CONCLUSION

The diagnosis is mainly clinical, based on the morphology of the lesion, the presence of a positive Darier sign, and the absence of systemic involvement. A skin biopsy is usually not necessary unless the diagnosis is in doubt.

Mastocytosis: from a Molecular Point of View

Mast cells (MCs) are physiologically activated by binding of stem cell factor (SCF) to the extracellular domains of the Kit receptor. This binding increases the proliferation and prolongs the survival of normal mature MCs, as well as intensifies the release of mediators. In mastocytosis, somatic mutations of the coding Kit gene cause autocrine dysregulation and lead to constitutive KIT activation even in the absence of its ligand SCF. Clinical symptoms are caused by MC-mediator release and/or infiltration of MCs into tissues. Aberrant KIT activation may result in increased production of MCs in the skin and extracutaneous organs. Depending on the affected organ(s), the disease can be divided into cutaneous mastocytosis (CM), systemic mastocytosis (SM), and localized MC tumors. The updated classification of WHO discriminates between several distinct subvariants of CM and SM. While the prognosis in CM and indolent SM (ISM) is excellent with (almost) normal life expectancy, the prognosis in aggressive SM (ASM) and MC leukemia (MCL) is dismal. The symptoms may comprise urticaria, angioedema, flush, pruritus, abdominal pain, diarrhea, hypotension, syncope, and musculoskeletal pain and are the results of MC infiltration and mediator release into target organs, i.e., the skin, gastrointestinal tract, liver, spleen, lymph nodes, and bone marrow. Mastocytosis differs from a lot of other hematological disorders because its pathology is not only based on the lack of normal function of a specific pathway or of a specific cell type but additionally is a proliferative disease. Currently available treatments of mastocytosis include symptomatic, antimediator and cytoreductive targeted therapies.