CPC06 Congenital urticaria pigmentosa mistaken for nonaccidental injury

Abstract A male infant presented to his general practitioner for a routine 6-week check. His parents reported the presence of tan–brown lesions since birth. The marks were uniform in colour, present on trunk, scalp and face, not overlying bony prominences. There was concern that these represented bruising as manifestation nonaccidental injury (NAI), urgent paediatric review arranged. He admitted investigation potential NAI, dermatology consultation sought. On examination, scattered reddish brown-to-tan macules papules noted torso limbs, Darier sign negative, although some reactive cutis marmorata appreciable trunk following rubbing multiple lesions. diagnosis urticaria pigmentosa (UP), or cutaneous mastocytosis, made clinically. Skin biopsies demonstrated an infiltrate spindled round mast cells eosinophils within superficial mid-dermis, with immunohistochemistry positive CD117, consistent UP. Blood tests during admission showed normal complete blood count coagulation screen (including von Willebrand factor), renal liver function, lactate dehydrogenase, immunoglobulins cell tryptase. Cranial ultrasound normal. Mastocytosis is spectrum disease characterized by pathological accumulation tissues, including skin, bone marrow gastrointestinal tract. Cutaneous mastocytosis can be further classified maculopapular also known UP, diffuse localized mastocytomas. With children typically first 2 years life reddish-brown macules, and/or plaques distributed anywhere body, most commonly trunk. In darkly pigmented may hyperpigmented erythema less appreciable. sign, transient urticarial response upon gentle classic supportive diagnosis, it always demonstrable. UP has rarely been misdiagnosed NAI. Other ‘bruising’ mimics include disorders coagulation, Valsalva petechiae, vasculitis, acute haemorrhagic oedema, incontinentia pigmenti, phytophotodermatitis, coin rubbing, spooning, cupping, Mongolian spots, morphoea, neuroblastoma ink stains, which unfamiliar paediatricians dermatologists. Dermatologists have crucial role recognizing manifestations NAI children, includes bruising, particularly infants who are yet mobile. While consideration important all presenting medical care, this case highlights importance considering underlying dermatoses avoid unwarranted distress unnecessary investigations.