Photo Rounds

Incidental skin finding

During a routine visit to establish care at the Family Medicine Clinic, the physician noted numerous pink to tan maculopapular lesions on this 26-year-old woman’s arms, back, and neck. She said she’d had the lesions since childhood and that they got worse with cold weather and scratching.

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References

Incidental skin finding

This patient was given a diagnosis of cutaneous mastocytosis. The condition was previously known as urticaria pigmentosa, but in 2016 the World Health Organization reclassified the disease to better suit its pathophysiology as a myeloid cell disorder.1

As the name suggests, this condition—which involves lesions in a sporadic, truncal distribution—involves overactivation of mastocytes at the tissue level from various stimuli, resulting in histocyte degranulation and hyperpigmentation. The exact cause is unknown. What is known is that it is often associated with other allergic or immunologic conditions and is thought to be related to mutations in the gene for CD-117’s receptor for tyrosine kinase.1 Incidence is similar to that of asthma, in that it occurs more often in younger patients; a majority of affected individuals will grow out of the disease by adolescence.1

Although most patients do not experience severe symptomatology, it is still important to differentiate cutaneous vs systemic mastocytosis. If a patient presents with inexplicable systemic symptoms of malaise, vague abdominal pain, heartburn, or flushing, the physician should consider systemic mastocytosis, idiopathic anaphylaxis, or hereditary alpha-tryptasemia.2

The test of choice is a serum tryptase test; levels will be elevated with systemic mastocytosis. Consider obtaining a skin biopsy if lesions are ambiguous or nondistinct.

There is no definitive cure for systemic or cutaneous mastocytosis, so treatment is directed at symptoms. Start by advising patients to avoid triggers and to refrain from scratching the affected areas. Topical antihistamines and oral nonsedating antihistamines can be helpful. If symptoms are more severe, refer the patient to an allergist/immunologist or to a hematologist for further medical management.2

The patient in this case had no systemic symptoms, so she was advised to continue taking oral loratadine 10 mg/d, which had been helpful, and to avoid rubbing her skin.

Image courtesy of Daniel Stulberg, MD. Text courtesy of Murtaza Rizvi, MD, and Daniel Stulberg, MD, FAAFP, Professor and Chair, Department of Family and Community Medicine, Western Michigan University Homer Stryker, MD School of Medicine, Kalamazoo.

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