Aggressive Systemic Mastocytosis with a Relatively Non-aggressive Course

Abstract

Background: Mastocytosis is a heterogeneous group of disorders that is characterized by excessive proliferation and pathologic accumulation of mast cells in various body tissues. The mast cells also have abnormal morphology and aberrant expression of surface receptors. Clinical Description: A 4-year-old boy was brought with a history of generalized skin lesions since birth and abdominal distension for 3 years. The diagnosis had not been established to date. General physical examination revealed severe acute malnutrition, pallor, dental staining, facial hypertrichosis, polymorphous skin lesions (cicatricial alopecia, diffuse erythema, multiple plaques of variable diameter, skin-colored nodules, and hypertrophic irregular scars), and positive Darier's sign. He also had hepatosplenomegaly. The differentials considered were congenital erythropoietic porphyria, systemic mastocytosis (SM), multifocal Langerhans cell histiocytosis, and linear immunoglobulin A bullous dermatosis. The presence of mast cells on skin biopsy and elevated serum tryptase levels led us to suspect SM and perform bone marrow studies. The diagnosis of “aggressive” SM was initially made on the application of the diagnostic criteria but revised to “smoldering” SM with the emergence of Vitamin B12 deficiency as the probable cause of pancytopenia. Management: Management was planned by a multidisciplinary team: pediatrician, dermatologist, and hematopathologist. The parents were counseled about the nature, natural history, treatment options, and prognosis of the disorder. The child was provided with nutritional rehabilitation and medication for the cutaneous symptoms (selective histamine H1 receptor inverse agonist, H2-receptor antagonist, and application of topical tacrolimus and calamine lotion). Conclusion: The prognosis varies according to subtype. Careful correlation of clinical and laboratory investigations is required when applying the diagnostic criteria for staging.