Congenital urticaria pigmentosa mistaken for non-accidental
injury
Emma Porter MD, 1 Cynthia Heffron MD, PhD,2 Lesley Ann Murphy MD, 1 Cathal
O’Connor MD 1, 3
- Dermatology, South Infirmary Victoria University Hospital, Cork,
Ireland
- Pathology, Cork University Hospital, Cork, Ireland
- INFANT Research Centre, University College Cork, Cork, Ireland
Corresponding author: Cathal O’Connor,
cathal.oconnor@ucc.ie
Word count: 492
Figure count: 2
References: 5
Conflict of interest: None
Consent statement: Written informed consent was obtained from the
patient’s parents to publish this report in accordance with the
journal’s patient consent policy.
A previously well male infant presented to his general practitioner (GP)
for his routine 6-week check. His parents reported the presence of
tan-brown lesions since birth. The marks were uniform in color, were
present on the trunk, scalp, and face, and were not overlying bony
prominences. The GP was concerned that these lesions represented
bruising as a manifestation of NAI, and arranged urgent review at our
pediatric department. Following assessment by the pediatric team he was
admitted for investigation of potential NAI, and dermatology
consultation was sought. On examination, scattered reddish brown to tan
macules and papules were noted on the torso and limbs, not overlying
bony prominences (Figure 1A, 1B). Darier sign was negative, although
some reactive cutis marmorata was appreciable on the trunk following
rubbing of multiple lesions. A diagnosis of urticaria pigmentosa (UP),
or cutaneous mastocytosis, was made clinically. Skin biopsies
demonstrated an infiltrate of spindled and round mast cells and
scattered eosinophils within the superficial and mid dermis, with
immunohistochemistry positive for CD117, consistent with UP (Figure
2A-2C). Blood tests during admission showed a normal complete blood
count and coagulation screen (including von Willebrand factor), normal
renal and liver function, normal lactate dehydrogenase, normal
immunoglobulins, and normal mast cell tryptase. A cranial ultrasound and
liver ultrasound were normal.
Mastocytosis is a spectrum of disease characterised by pathologic
accumulation of mast cells in tissues, including skin, bone marrow and
the gastrointestinal tract. The World Health Organisation has outlined
three variants: cutaneous mastocytosis, systemic mastocytosis, and mast
cell sarcoma. Cutaneous mastocytosis can be further classified as
maculopapular cutaneous mastocytosis, also known as UP; diffuse
cutaneous mastocytosis; and localised cutaneous mastocytomas.1 Paediatric cutaneous mastocytosis is regarded as a
benign condition limited to skin, most commonly presenting as UP, which
usually spontaneously regresses in puberty. 2 In
contrast, adult-onset mastocytosis is more often associated with
systemic involvement, a persistent course, and activating mutations of
the KIT gene. 1
With UP, children typically present in the first two years of life with
multiple reddish-brown macules, papules and/or plaques distributed
anywhere on the body, most commonly the trunk. In darkly pigmented skin,
lesions may be hyperpigmented and erythema less appreciable. Darier
sign, a transient urticarial response upon gentle rubbing of the skin,
is classic and supportive of diagnosis, though not always demonstrable.
Treatment with antihistamines can be helpful. 3 UP has
rarely been reported to be misdiagnosed as NAI. 4, 5Other ‘bruising’ mimics include disorders of coagulation, Valsalva
petechiae, vasculitis, acute haemorrhagic edema, incontinentia pigmenti,
phytophotodermatitis, coin rubbing, spooning, cupping, Mongolian spots,
morphea, neuroblastoma, and ink stains, some of which may be unfamiliar
to pediatricians or dermatologists.
Dermatologists have a crucial role in recognising cutaneous
manifestations of NAI in children, which commonly includes bruising,
particularly in infants who are not yet mobile. 4While consideration of NAI is important in all children presenting for
medical care, this case highlights the importance of considering
underlying dermatoses to avoid unwarranted distress and unnecessary
investigations.