Urticaria pigmentosa

Introduction

Urticaria pigmentosa is the most common variant of cutaneous mastocytosis. The disease in-cludes urticaria pigmentosa, mastocytoma, telang-iectasia macularis eruptiva perstans, diffuse masto-cytosis and systemic mastocytosis. Mastocytosis is uncommon in any form.[1],[2] In about 70-75% of cases, lesions of mastocytosis are evident before the age of 2 years.[3] A typical case of this dermatosis is being presented.

Case Report

A-2-year- old female child presented with generalized eruption of multiple brownish macular and papular lesions on the trunk and limbs of one year duration. There was history of generalised urti-carial flushing and bulla formation. There was no family history of similar disease and the general health, growth and development of the child was unaffected.

On examination, there were multiple hyper -pigmented papular lesions on the trunk and limbs. However, there were no bullae at the time of exami-nation. On stroking the individual lesion, there was formation of wheal and erythema (Darier′s sign- posi-tive). There was no hepatosplenomegaly or lymphad- enopathy.

Histopathological examination of lesional skin showed infiltration of numerous mast cells in perivas-cular and periappendageal location in the upper der-mis. There were no nodular aggregates or sheets of mast cells. Mast cell granules were demonstrable on metachromatic stain as bluish purple granules [Figure - 1]. A few eosinophils were also present in the dermis. Overlying epidermis showed increased amount of melanin and many melanophages were scattered in the upper dermis. Features were consistent with the clinical diagnosis of urticaria pigmentosa. Complete blood count, liver and renal functions, urinanalysis and chest roentgenogram were normal. Lesions re-gressed with topical application of fluocinolone acetonide, 0.01% ointment applied twice daily along with administration of chlorpheniramine maleate, 2 mg thrice daily for four weeks. Necessary advice to parents was given regarding avoidance of excessive scrubbing and massage of the skin. At the end of 8 weeks the child had only residual pigmentation left at the lesional sites with no new lesion formation.

Discussion

Urticaria pigmentosa is a rare disorder of mast cell infiltration. Primarily a disease of childhood, in over half the cases onset is before the age of 2 years and in 90% the disease is confined to the skin.[4] Lesions which manifest in childhood usually improve by puberty. Exact aetiology is not known. However, it is believed to be proliferation of mast cells medi-ated through cytokines. Interestingly the prognosis is best in childhood cases; bullae formation, how-ever extensive, is not a sign of poor prognosis.

Present case is a typical case of cutaneous mastocytosis without systemic involvement which responded well to symptomatic treatment with topi-cal corticosteroid and H1 antihistaminics.

Acknowledgement

The contribution of Dr. G.P. Thami, Reader, Department of Derma-tology & Venereology is gratefully acknowledged.