Clinicopathological Profile of Childhood Onset Cutaneous Mastocytosis from a Tertiary Care Center in South India

Abstract

Background: Mastocytosis is characterized by clonal proliferation of mast cells in various organs and can have isolated cutaneous or systemic involvement. Childhood-onset mastocytosis (COM) is usually cutaneous and regresses spontaneously, while adult-onset mastocytosis (AOM) is often persistent with systemic involvement. There is limited data on COM from India.

Objective: To elucidate the clinicopathological profile of COM.

Methods: We conducted a retrospective chart review of all the patients with histologically proven COM (≤16 years), presenting over 11 years (January 2009 to December 2019) to the Dermatology Department. We compiled the demographic data, clinical characteristics (morphology, extent, distribution), laboratory investigations, histopathology findings, imaging (ultrasound abdomen), c-KIT mutation results, where available, and other associated abnormalities, and grouped them according to the WHO classification for mastocytosis.

Results: Among the 66 patients with COM (M: F-1.6:1), 89.4% had onset before 2 years of age. The subtypes were: maculopapular cutaneous mastocytosis (MPCM: 44, 66.7%); mastocytoma of the skin (MOS: 19, 28.8%); diffuse cutaneous mastocytosis (DCM: 2, 3%) and indolent systemic mastocytosis (ISM: 1, 1.5%). Blistering was observed in 29 (43.9%) and Darier sign was elicited in 47 (71.2%) patients. Serum tryptase was elevated in 9/21 (42.9%) patients, but none had systemic mastocytosis. Three patients had c-KIT mutations (two in exon 8 and one in exon 17). Most patients were managed symptomatically and the patient with ISM improved with imatinib.

Conclusion: MPCM is the most common variant of COM and most patients had a disease onset before 2 years. Overall, COM had a good prognosis with rare systemic involvement, mitigating the need for extensive evaluation routinely in children.

Keywords: Childhood mastocytosis; c-KIT; cutaneous mastocytosis; mastocytoma; pediatric mastocytosis; tryptase; urticaria pigmentosa.

Figure 1

Patient flow chart.

Figure 2

(a) Multiple light brown to hyperpigmented macules in a patient with MPCM, (b) positive Darier sign in MPCM, (c) yellowish pseudoxanthomatous plaques on the neck of a patient with MPCM, (d) diffuse MPCM with multiple plaques, (e) MPCM with plaques showing blistering and ulceration, (f) solitary mastocytoma of the skin with positive Darier sign, (g) diffuse infiltration of the skin (h) with blistering in diffuse cutaneous mastocytosis.

Figure 3

Histopathology showing (a) dense diffuse infiltrates of mast cells in the upper third of the dermis (H and E, 50X), insert (H and E, 100X); (b) telangiectasia with mild perivascular infiltrates of lymphocytes and scattered mast cells in the superficial dermis, basal layer hyperpigmentation (H and E, 100X); (c) proliferated blood vessels with moderate aggregates of mast cells admixed with occasional lymphocytes and histiocytes (H and E, 100X); (d) intraepidermal bulla with diffuse and perivascular aggregates of mast cells in the dermis (H and E, 50X) (e) Mast cells highlighted using toluidine blue stain (200X); (f) CD117 positive mast cells (immunoperoxidase stain, 100X)

Figure 4

Sanger sequencing electropherogram of the c-KIT mutations identified in exon 17 and 8 in this study.