Patrick McLaughlin, MD, MS
A three month old male born at 39 weeks gestation, with a history of a possible seizure disorder, presents two hours after a large fluid-filled lesion developed on his left forearm. Immediately before he developed this lesion his entire body became red and flushed for 15 minutes then spontaneously resolved. The fluid-filled lesion shown developed on top of a skin lesion that had previously been present since 1 week of life. At 2 months of age he experienced these exact symptoms for which he was hospitalized overnight at another institution. During that admission, the bulla’s fluid was cultured for bacteria but was negative for growth. He completed a 10 day course of oral clindamycin and topical mupirocin without resolution of the lesion. Family denies any fever, purulence from the lesion, sick contacts, burns, pets or changes in the patient’s behavior.
On physical examination he had a pulse of 135 beats per minute, blood pressure of 1118/73 mmHg, temperature of 98.8 F (37.1 C), respiratory rate of 32 and oxygen saturation of 100% on room air. He was well appearing and interactive with age appropriate behavior. He had no evidence of generalized flushing, rash or urticaria. The skin lesion shown was 2 cm in diameter with thickened skin that was orange/pink in color and had a tense 1 cm bulla with clear fluid on top. No surrounding erythema, swelling or warmth.
The differential diagnosis includes local/contact dermatitis, local reaction to an insect bite or envenomation, bullous impetigo or a congenital skin lesion such as a self-healing reticulohistiocytosis, cutaneous mastocytosis or the cutenous manifestation of malignancy. Our patient was diagnosed with a cutaneous mastocytoma after consultation of our dermatology department.
Patients may present with cutaneous or systemic mastocytosis. Infants will typically present with a solitary mastocytoma. Some have a yellowish or orange coloration. Bullae may appear with local irritation of the lesion as well as generalized flushing and pruritis of the skin (local or systemic), however generalized urticarial and angioedema are rare. Systemic symptoms are mediated by non-specific mast cell-mediator release and therefore patients should avoid irritating the lesion(s), particularly if they are susceptible to the generalized reactions. Acutely they may develop nausea, vomiting and diarrhea as well as vasodilation, tachycardia and secondary hypotension. Infants have also been described to develop secondary apneic spells and cyanosis.
Management is observation and education in addition to a dermatology referral for this rare skin condition. Most lesions resolve spontaneously in months to years.