INTRODUCTION: Cutaneous mastocytosis is the accumulation of mast cells in the skin. Diffuse cutaneous mastocytosis is a rare variant accounting for only 1.74% of al mastocytosis cases reported. Ninety percent of cases are seen in children presenting with multiple erythematous to yellow-tan papules and plaques with leathery texture. The pathogenesis is in the structure and activity of kit receptor expressed on mast cells, melanocytes and other cells. CASE SUMMARY: This is a female neonate born to an 18 year old mother, G1P1 via vaginal delivery at 37 weeks age of gestation. Patient presented with a generalized involvement of multiple, well defined, indurated, leathery, brown papules and confluent plaques. Darier sign was positive. Histopathological examination revealed diffuse involvement of the dermis with mast cells. Giemsa stain was positive. Patient was diagnosed both clinically and histopathologically with diffuse cutaneous mastocytosis without systemic involvement. She was treated with H1 antihistamines and topical glucocorticoids. CONCLUSION Diffuse cutaneous mastocytosis can be diagnosed both clinically and histopathologically. Treatment is mostly symptomatic. It is always prudent to inform co-managing physicians, the patient, and their families of potential mast cell degranulating stimuli and to watch out for signs and symptoms for systemic involvement.