Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.
A 40-year-old woman is evaluated for a rash on her hands that has been present for 6 weeks. This rash comes and goes throughout the year and has been present for many years, but never as severe as it is now. She also experiences itchy skin on her body. She had eczema as a child and currently has seasonal allergies. She is otherwise well and is currently taking no medication.
On physical examination, vital signs are normal. She has dry skin on her trunk and extremities. Her hands are extremely dry with scaling, erythema, and fissuring on the dorsal hand surfaces. Her feet are not involved.
Which of the following is the most likely diagnosis?
A: Atopic hand dermatitis
B: Keratoderma blenorrhagica
C: Scabies
D: Tinea manuum
MKSAP Answer and Critique
The correct answer is A: Atopic hand dermatitis.
This patient with a previous history of atopic dermatitis has hand dermatitis. Atopic dermatitis is a chronic, pruritic skin condition that begins in childhood. The course is marked by intermittent flares, but generally becomes less severe with age. Adults with atopic dermatitis, such as this patient, may outgrow their childhood eczema but may subsequently develop hand dermatitis. Adult manifestations of atopic dermatitis include “sensitive” skin, hand dermatitis, or persistent eczema. Hand dermatitis is often work-related and may result in absenteeism or a change of profession. Occupations that involve frequent or prolonged contact with water or solutions (“wet work”) have a high prevalence of hand dermatitis. Diagnosing hand dermatitis can be difficult, as the results of a skin biopsy may be nonspecific. Patch testing should be considered. Scrapings for potassium hydroxide (KOH) examination and oil preparation for scabies should be performed when considering the diagnoses of fungi, yeast, or scabies.
Keratoderma blenorrhagica is a hyperkeratotic skin condition usually presenting as erythematous scaly plaques of the palms and soles that is associated with spondyloarthropathy, a disease formerly known as Reiter syndrome. The patient’s hand findings and lack of other symptoms make this diagnosis unlikely.
Scabies infestation causes intense itching and a papular or vesicular rash. Burrows are visible as short, serpiginous lines. Location in the interdigital webs, flexure surface of the wrists, penis, axillae, nipples, umbilicus, scrotum, and buttocks is diagnostic. Scabies infestation should be suspected whenever a patient and close contacts are itching. This history and findings are absent in this patient.
Tinea manuum is a dermatophyte infection involving the hand. Dermatophytes are the most common fungi that infect skin. Dermatophytes infect the highest level of the epidermis, the stratum corneum, where they cause bothersome, often itchy rashes. Tinea manuum characteristically involves only one hand (and two feet). The findings are characterized by a dry scale, and if chronic, nails can be involved. The diagnosis of tinea manuum is unlikely if the feet are not involved.
Key Point
- Hand dermatitis is more common in patients with atopic eczema and is often exacerbated by frequent or prolonged contact with water or harsh substances.
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