The Journal of the Arkansas Medical Society Med Journal April 2020 | Page 14

derm dilemma Special Section: Short Dermatological Cases by Kyle Sandiford, MD candidate, Class of 2021 Logan Rush, MD, Resident, UAMS Dept of Dermatology A nine-month-old male presents to his pediatrician is the most common presenting variant of masto- is exposed to a warm bath). Other culprits of mast with hyperpigmented macules of the arms, back, cytosis in the pediatric population, accounting for cell stimulation include certain drugs (salicylates, and abdomen that have been noticeable for the more than 80% of mastocytosis diagnoses in this NSAIDs, narcotics), exercise, various food-stuffs, past three months. At birth, the child had a simi- group. This condition can be divided into a poly- and even local trauma or tactile stimulation (Darier’s lar lesion present on the neck that has persisted. morphic and monomorphic subtype. Polymorphic sign). Darier’s Sign, a bedside test to help confirm UP is characterized by multiple lesions that vary the suspicion of UP, is wheal formation at the lesion These macules become raised and red “whelps” in shape and size and are typically located on the elicited by firmly stroking one of the hyperpigmented after bathing, pressure or exposure to the outdoor neck, face, back, abdomen, and/or extremities of the macules. These stimuli provoke mast cell activation heat, causing significant itching and irritability. In affected individual; in contrast, the monomorphic and degranulation, permitting the release of various addition, the lesions often flare at night, disrupting subtype is noted for lesions of uniform shape and molecules such as histamine, eicosanoids (pros- the patients’ sleep. The parents express concern that size resembling lesions of the adult UP variant and taglandins and leukotrienes), and heparin, among these markings are bruises that will not resolve, and generally carries a poorer prognosis with respect other molecular intermediaries. These biochemical request an investigation for possible abuse. No evi- ligands act in coordination to target their respective dence for such is found. Subsequently, blood panels receptors, initiating inflammatory messenger cas- to investigate a concern for vasculitis, panniculitis or cades that instigate the various signs and symp- blood dyscrasias are performed and show normal toms associated with mast cell degranulation. Pru- results. ritus, erythema, and edema quickly ensue. Though UP is defined by mastocyte containment within the The most appropriate next step in the diagnosis and skin itself, systemic signs such as fatigue, nausea, management of this patient’s condition includes and vomiting can present in these patients as well. which of the following? Treatment of UP is largely targeted at symptom A Reassure the parents, as this eruption rep- management. Traditionally, the literature has sug- resents urticaria pigmentosa, a cutaneous gested that the condition will spontaneously resolve variant of mastocytosis that typically re- in over 50% of cases before the child reaches ad- solves spontaneously prior to adolescence. olescence. However, this consensus has recently Prescribe 2.5% topical hydrocortisone for been challenged, as some studies suggest that periodic relief of symptoms and educate many of these reported cases of complete resolu- the family on potential exacerbating factors. tion have quite simply been overstated. Cutaneous symptom alleviation can be achieved with topical B. The lesions are café au lait macules. The physi- steroid ointments or calcineurin inhibitors. Antihis- cian should initiate genetic testing, looking spe- tamines, specifically second-generation agents (i.e. cifically for mutations in the NF1 gene of chro- to the extension of the disease into adulthood. The cetirizine), have shown to have some clinical bene- mosome 17 that are implicated in Neurofibro- lesions of UP represent coalescing mast cells that fit in the prevention of skin-specific symptoms that matosis Type I (Von Recklinghausen disease). over proliferate in response to various KIT gene arise as a result of UP. Educating the family and the mutations, most notably the D816V constitutive patient about avoidance of potential triggers is para- C. Reassure the parents that the marks on the activating mutation. Urticaria pigmentosa is a clini- mount in future prevention of disease exacerbation. child’s body are congenital nevi, and that the cal diagnosis resulting from a thorough history and Interestingly, the presence of the KIT mutation has signs of irritability with heat exposure are de- physical examination; however, definitive diagnosis led some to suggest the potential therapeutic ben- velopmentally appropriate responses of young is confirmed with an H&E stain of the biopsied le- efit of monoclonal antibodies and other classes of children to previously unrecognized stimuli. sion. Diagnostic criterion requires more than 15 molecular inhibitors. Though UP is characterized as mast cells per cluster or scattered mast cells with a benign process, yearly monitoring for progression D. Immediate biopsy of the lesion(s) to confirm greater than 20 mast cells per high powered field. of the disease into systemic mastocytosis should be the diagnosis of systemic mastocytosis. Begin It is not uncommon to find upwards of a 40-fold initiated by evaluating for persistent abnormalities in systemic corticosteroids to mitigate symptoms concentration increase in mast cells in the dermis the CBC, elevated serum tryptase of >20ng/ml, sple- and minimize the risk of anaphylaxis. of sampled tissue as compared to normal skin. nomegaly, and/or persistent lymphadenopathy. The debilitating effects of UP should not be understated, Answer: A.) The clinical manifestations of UP in children are and prompt treatment for these patients will greatly Urticaria Pigmentosa (UP), otherwise known as typically confined to cutaneous symptomology and reduce the burden of the disease while increasing Maculopapular Cutaneous Mastocytosis (MCM), are often exacerbated by heat (i.e. when the child the longevity of those affected. 230 • The Journal of the Arkansas Medical Society www.ArkMed.org