What is causing this multi-finger asymptomatic lesion?


Case 1:
The mother of a 10-year-old boy brings him in for evaluation of his moles (which are all benign). During the visit, the mother asks about the lesions on the first 2 knuckles of his right hand; she initially noticed them several months earlier. The boy is otherwise healthy. What is your clinical impression?

A. Warts

B. Psoriasis

C. Lichen planus

D. Dermatomyositis

E. Trauma


Case 1: Trauma (knuckle biting)

Further questioning revealed that the patient had a “nervous,” or compulsive, habit of chewing and biting on his knuckles, E, especially during stressful situations at school.

Warts would have a more verrucous appearance, and psoriasis would be more erythematous and scaly. Lichen planus is characterized by polygonal purplish papules, which are unlike the changes seen here. Dermatomyositis can produce erythematous papules overlying the joints of the hands; however, these lesions are associated with proximal muscle weakness, which was absent in this healthy 10-year-old boy.


Case 2:
This asymptomatic lesion on the dorsum of a 15-year-old boy’s left hand extends on to the first 2 fingers and has produced nail dystrophy. The patient is otherwise healthy and denies any history of trauma to the hand. Which of the following would you include in the differential diagnosis?

A. Trauma.

B. Linear scleroderma

C. Linear lichen planus

D. Raynaud phenomenon

E. Linear epidermal nevus


Case 2: Linear scleroderma (linear morphea)

This patient had linear scleroderma, B, or linear morphea. These lesions may extend the entire length of the arm or leg. The childhood type of linear morphea may undergo spontaneous resolution. There is no FDA-approved treatment for this condition, although anecdotal reports describe numerous therapies that have been tried. Linear lichen planus usually presents with purple papules that appear in a straight line after trauma. A linear epidermal nevus has a wart-like appearance. Raynaud phenomenon can affect the vascular supply, but it is associated with color changes when the skin is exposed to cold temperatures.

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