Cutaneous mastocytosis, presentation of three cases

Abstract

Mastocytosis is a rare disorder characterized by neoplastic clonal proliferation of mast cells in one or more tissues, with cutaneous and/or systemic manifestations related to the KIT mutation. WHO classifies them as cutaneous mastocytosis (CM), systemic mastocytosis (SM) and sarcoma. CM includes maculopapular forms (monomorphic and polymorphic), diffuse cutaneous and mastocytoma. CM usually presents in the first six months of life with a tendency to disappear in adolescence. The location of the lesions depends on the type of mastocytosis, the most frequent form is maculopapular polymorphic one, with lesions of different sizes, reddish brown with edema, redness, itching and sometimes blistering. Darier's sign is pathognomonic. The diagnosis of cutaneous mastocytosis based on gross appearance is confirmed with skin biopsy showing an increased number of mast cells. Our purpose is the communication of three cases of CM in pediatric age with different clinical and morphologies manifestations highlighting the role of histochemical techniques and immunohistochemistry for the definitive diagnosis of the lesion.

PRESENTATION OF CASES

Case 1: Male patient presents a pruritic tumor in the right lower limb from 3 months and a similar one in the right arm. Darier negative.

Case 2: Male patient presents infiltrated erythematous papules with defined limits on the face, inframammary and suprapubic región, and erythematous-brown plaque in the right retroauricular región with similar characteristics.

Case 3: 4 year old female patient with Brown plaque-type lesions from birth that increased in number with growth, asymptomatic.

Biopsies were fixed in 10% formalin, embedded in paraffin, and stained with hematoxylin/eosin, histochemical techniques with toluidine blue and immunohistochemistry. Histological sections showed dermis occupied by a proliferation of mast cells, arranged according to the cases in a diffuse way, in nests and perivascular. They presented monomorphic nuclei and granular cytoplasms that stood out with toluidine blue techniques, being metachromatic. (+40 x mm2).  Immunohistochemical techniques for CD117 were performed, being all positive.

CONCLUSION: Our purpose was to present three forms of rare mast cell tumors, highlighting the need for its clinical and pathological differential diagnosis with other tumors, mainly with histiocytosis.