Race for the Case answers

Race for the Case Fall 2023 by Andrea Paola Caro Muñiz, MD, and Eduardo-Michelin Gomez, MD

A six-year-old female patient is seen at our outpatient clinics for evaluation of multiple scattered eczematous, scaly plaques overlying a hyperpigmented, hypertrichotic area extending from the patient’s left scapula down to her right dorsal hand (left image); the latter had been present since the patient was a one-year-old. Punch biopsy of the lesion revealed epidermal acanthosis with papillomatosis and hyperpigmentation of the basal layer, with numerous hairs in anagen stage. The patient was prescribed tacrolimus 0.1% ointment and triamcinolone acetonide 0.1% cream with significant improvement of the eczematous lesions (right image).

1. Which post-zygotic mutation has been associated with the development of this nevus?
Answer: AACTB, which encodes for beta-actin, has been implicated in the development of Becker’s nevus and Becker’s nevus syndrome.

2. Name the syndrome most commonly associated with this nevus.
Answer: Becker's nevus syndrome (part of the epidermal nevus syndromes): Becker's nevus with unilateral breast hypoplasia and muscle, skin, and/or skeletal abnormalities.

3. What is the phenomenon observed in the image on the left?
Answer: Wolf’s isotopic response phenomenon: the appearance of a new skin disorder at the site of another, unrelated, and often healed skin disease.

References

1. Cai ED, et al. Postzygotic mutations in beta-actin are associated with Becker’s nevus and Becker’s nevus syndrome. J Invest Dermatol 2017; 137: 1795-8.

2. Dasegowda SB, Basavaraj G, Nischal K, Swaroop M, Umashankar N, Swamy SS. Becker's Nevus Syndrome. Indian J Dermatol. 2014 Jul;59(4):421. doi: 10.4103/0019-5154.135530. PMID: 25071279; PMCID: PMC4103296.

3. Lee JS, Park HS, Yoon HS, Cho S. Becker's Nevus with Recurrent Eczema Limited to the Nevus Lesion. Ann Dermatol. 2018 Feb;30(1):83-86. doi: 10.5021/ad.2018.30.1.83. Epub 2017 Dec 26. PMID: 29386838; PMCID: PMC5762483.

4. Lee DJ, Kang HY. Eczema Confined to Becker's Nevus on the Face: The Behavior of Melanocytes during Inflammation. Ann Dermatol. 2012 Feb;24(1):99-100. doi: 10.5021/ad.2012.24.1.99. Epub 2012 Feb 2. PMID: 22363167; PMCID: PMC3283863.