Photo Quiz

Diffuse, Thick Scale on Both Hands


Am Fam Physician. 2018 Feb 1;97(3):205-206.

A 60-year-old woman with a history of nonverbal autism, intellectual disability, and quadriplegia presented with a nonhealing erosion of the left distal index finger and skin changes involving both hands. The patient was unable to provide further history.

Physical examination revealed bilateral thick, adherent, white-gray scaling and crusting involving the hands, fingers, and web spaces with associated fissures. Diffuse xerosis and fine scale on the head, neck, trunk, and other extremities were also noted (Figure 1).

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Based on the patient's history and physical examination findings, which one of the following is the most likely diagnosis?

A. Atopic dermatitis.

B. Crusted scabies.

C. Psoriasis.

D. Retention hyperkeratosis.

E. Tinea manuum.


The answer is B: crusted scabies (also called hyperkeratotic scabies and Norwegian scabies). Crusted scabies presents as a severe and highly contagious form of scabies, characterized by skin hyperinfestation with up to millions of Sarcoptes scabiei mites.1 The heavy mite burden leads to the development of scaly, white-gray, hyperkeratotic plaques typically localized to the scalp, face, hands, feet, or buttocks. Plaques are often associated with deep fissures, making patients prone to secondary bacterial infections and increased risk of sepsis.2

Crusted scabies is most common in individuals with severe immunosuppression (e.g., from human immunodeficiency virus infection or use of immunosuppressant therapy). However, it also occurs in patients with cognitive impairment or physical disabilities who are unable to scratch to decrease the mite burden. Scabies is transmitted by direct skin-to-skin contact, although transmission from

Address correspondence to Eric C. Parlette, MD, at Reprints are not available from the authors.

Author disclosure: No relevant financial affiliations.


show all references

1. Yari N, Malone CH, Rivas A. Misdiagnosed crusted scabies in an AIDS patient leads to hyperinfestation. Cutis. 2017;99(3):202–204....

2. Walton SF, Beroukas D, Roberts-Thomson P, Currie BJ. New insights into disease pathogenesis in crusted (Norwegian) scabies: the skin immune response in crusted scabies. Br J Dermatol. 2008;158(6):1247–1255.

3. Ortega-Loayza AG, McCall CO, Nunley JR. Crusted scabies and multiple dosages of ivermectin. J Drugs Dermatol. 2013;12(5):584–585.

4. Centers for Disease Control and Prevention. Scabies. Treatment. Accessed July 20, 2017.

5. Eichenfield LF, Tom WL, Chamlin SL, et al. Guidelines of care for the management of atopic dermatitis: section 1. Diagnosis and assessment of atopic dermatitis. J Am Acad Dermatol. 2014;70(2):338–351.

6. van de Kerhof PC, Nestle FO. Psoriasis. In: Bolognia JL, Jorrizzo JL, eds. Dermatology. 3rd ed. Philadelphia, Pa.: Elsevier Saunders ;2012:135–156.

7. Harris K, Pho LN, Bowen AR. Severe retention hyperkeratosis occurring with Susac syndrome. Dermatol Online J. 2010;16(10):8.

8. Noble SL, Forbes RC, Stamm PL. Diagnosis and management of common tinea infections. Am Fam Physician. 1998;58(1):163–174.

This series is coordinated by John E. Delzell Jr., MD, MSPH, Associate Medical Editor.

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