Urticaria pigmentosa

Abstract

We report a case of solitary mastocytoma in a child which was successfully treated with a topical steroid of moderate potency. The patient was an 18-month-old girl who presented with localized oval shape yellowish to hyperpigmented lesion on the medial aspect of her right forearm noticed accidentally by the parents since the age of 6 months. The lesion was observed to get urticated mainly after bathing, toweling, and scratching of the area, associated with reddening and itching confined to the lesion (Figure 1). No other area of the body was affected with any similar lesion.

Examination of the skin revealed a yellow-tan oval shape patch 1 X 3 cm in diameter which was firm to the touch with intact overlying skin. The lesion became swollen and itchy when it was rubbed vigorously (positive Darier's sign). Systemic examination was unremarkable. The patient investigations including complete blood count, routine biochemical data, plasma histamine level, and urinalysis were within normal levels. Skin biopsy was cancelled because the parents refused, so our clinical diagnosis was solitary mastocytoma even though it was not confirmed histologically. We started the patient on a moderate potency corticosteroid (betamethasone valerate 0.1% cream) twice a day for six weeks after which the lesion became softer with a weak Darier's sign. This treatment was continued for another four months which led to resolution of the lesion with residual hyperpigmentation, negative Darier's sign, and no signs of atrophy (Figure 2). Follow up of the patient for another 8 weeks without treatment did not reveal any recurrence of the lesion.

**********

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

Solitary mastocytoma is a condition that occurs in infants characterized by localized mast cell hyperplasia and release of their mediators. It is one of the common manifestations of pediatric mastocytosis followed by urticaria pigmentosa (1). It usually appears in infants before their sixth month as a single rounded hyperpigmented macular, tuberous, or nodular lesion which grows gradually over a period of several months up to 4 cm in diameter, at which point the lesion stabilizes and tends to regress for as long as up to 7 years (2-5). Pruritis is the primary presenting symptom in children with mastocytosis, which could be intermittent or continuous, and associated with large areas of excoriation. Additional systemic symptoms such as vomiting, colicky pain, diarrhea, headache, and bullae are to be expected in patients with urticaria pigmentosa or diffuse cutaneous mastocytosis. The diagnosis is based on the clinical appearance of the lesions and elicitation of Darier's sign, and confirmed by biopsy which shows mast cell hyperplasia (6).

Spontaneous total regression is the natural course in 25% of mastocytoma cases; in another 25% the regression is partial, which indicates that treatment is not often recommended (5,6). The rest are usually treated symptomatically by H1 and H2 blockers and mast cell stabilizing agents such as sodium cromoglycate. Strong topical steroids and intralesional triamcinolone injections are used over limited areas only. They exert their effect through inhibition of histamine release and other mediators by mast cells and reducing mast cell number by inhibiting polymorphonuclear leukocyte chemotaxis. Though these effects are more pronounced with the use of more potent topical steroids, there is risk of developing atrophy if used for many months continuously (7-10). In our case we used a moderately potent topical steroid (betamethasone valerate) twice a day for a total of 22 weeks without occlusion which resulted in resolution of the lesion with hyperpigmentation but with no signs of atrophy or other side effects related to topical steroids. In conclusion, this case demonstrated the effect of using a less potent steroid in solitary mastocytoma to speed its resolution without worrying about the side effects caused by potent steroids.

Referencess:

1. Kacker A, et al. Solitary mastocytoma in an infant-case report with review of literature. Int J Pediatr Otorhinolaryngol 2000; 52:93-95.

2. Chargin L. Sachs P. Urtecaria pigmentosa appearing as solitary nodular lesion. Arch Dermatol Syphil 1954; 69:345-355.

3. Dermis J. The mastocytosis syndrome: clinical and biological studies. Ann Intern Med 1963; 59: 194-206.

4. Longley J, Duffy T, Khon S. The mast cell and mast cell disease. J Am Acad Dermatol 1995; 32:545-561.

5. Torrelo A, et al. Diagnostico, tratamiento y classification de la mastocitosis pediatrica. Estodio de 172 casos. Actas Dermosifilioger 1998; 89:461-476.

6. Loubeyres S, et al. Classification and management of mastocytosis in the child. Ann Dermatol Venereol 1999; 126: 20-25.

7. Soter NA. The skin in mastocytosis. J Investi Dermatol 1991; 96(suppl.):32S-39S.

8. Guzzo C, et al. Urtecaria pigmentosa. Systemic evaluation and successful treatment with topical steroid. Arch Dermatol 1991; 127:191-196.

9. Lavker R, Schecher N. Cutaneus mast cell depletion results from topical corticosteroid usage. J Immunol 1985; 35:2368-2373.

10. Mateo J. Mastocytoma: topical corticosteroid treatment. J Eur Acad Dermatol Venereol 2001; 15:492-493.

IQBAL A BUKHARI MD

ASSISTANT PROFESSOR AND CONSULTANT DERMATOLOGIST DERMATOLOGY DEPARTMENT, COLLEGE OF MEDICINE, KING FAISAL UNIVERSITY HOSPITAL ALKHOBAR, SAUDI ARABIA

ADDRESS FOR CORRESPONDENCE:

Iqbal A Bukhari MD

Assistant Professor

Dermatology Dept., College of Medicine

King Faisal University Hospital

PO Box 40189

Alkhobar 31952, Saudi Arabia

E-mail: consultant@dermatologyclinics.net

COPYRIGHT 2004 Journal of Drugs in Dermatology
COPYRIGHT 2004 Gale Group