A 4-year-old girl presented for evaluation of a localized hyperpigmented rash of 4 months duration. The family noticed a localized, brown discoloration on her anterior neck. It was asymptomatic. Her mother tried scrubbing the area with several different soaps and baby wipes, but noted no change. Her medical history is notable for atopic dermatitis, well controlled with intermittent topical corticosteroids, and reactive airway disease. There is a family history of atopic dermatitis and type 2 diabetes.
On physical exam, the patient is a non-obese (BMI 16 kg/m2) female with a 4 x 3–cm hyperpigmented, rough, slightly elevated plaque on her anterior neck. (See photo.) On close inspection, the plaque appears to be composed of hyperpigmented rugations. Viewed through a dermatoscope, the lesion’s polygonal brownish pigmentation looks like cobblestones ( Can Med Assoc J. 2016;188:285 ).The patient had no discoloration on the posterior neck, axillae, groin, or other locations.
Blood work, ordered by a practitioner concerned about possible acanthosis nigricans, revealed:
• CBC: within normal limits
• Glucose: 82 mg/dL (normal 60-110)
• Insulin: 3 mU/mL (normal less than 17)
• Cholesterol: 136 mg/dL (normal less than 200)
• Triglycerides: 79 mg/dL (normal 32-116)
• Thyroid-stimulating hormone: 1.72 uIU/mL (normal 0.35-5)
Rubbing the hyperpigmented area with a 70% isopropyl alcohol swab in clinic removed it completely. (See photo.)
What is your diagnosis?
1. Acanthosis nigricans
2. Confluent and reticulated papillomatosis
3. Dermatosis neglecta
4. Terra firma-forme dermatosis
5. Tinea versicolor