Dermatology Online Journal

Atypical Crusted Scabies in an Iranian man
Mohammad Reza Namazi and Behrooz Barikbin
Dermatology Online Journal 8(2): 17

From the Dermatology Department, Tehran University of Medical Sciences, Iran

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Abstract

Crusted scabies has been defined as a scabies-induced psoriasiform dermatosis on the hands and feet with dystrophy of the nails and an erythematous scaling eruption that may be generalized. This case report demonstrates a patient who presented with widespread psoriasiform plaques that were teeming with scabies mites and eggs, but who had absence of nail and palmar involvement. While patients with crusted scabies may have nail dystrophy and involvement of the palms, this involvement is not necessary.

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A 70-year-old man, apparently in good condition, presented to our clinic for evaluation of a pruritic eruption from which he had been suffering for 6 weeks.

Figure 1	Figure 2
Fig.1: The upper back and posterior aspect of the right arm demonstrate the presence of psoriasiform plaques.
Fig.2: There are additional plaqes involving the lower back and posterior right forearm.

Figure 3	Figure 4
Figure 3 demonstrates normal palms in this patient.
Figure 4 demonstates some involvement of the skin on the dorsum of the hand, but an absence of nail dystrophy.

Figure 5	Figure 6
Figs.5 and 6 are low and medium power images of scrapings from this patient. The low power image demonstrates multiple mites.

The patient had no history of significant medical problems and his general physical examination was normal. His skin examination revealed large erythematous, hyperkeratotic, scaly plaques on the trunk, abdomen, and extremities, as well as numerous small erythematous papules with scattered excoriations. His head, as well as his palmar and plantar surfaces were free of any lesions. The nails were normal as well. (Figure 4).

The presence of itching in the patient's family members made us concerned about a possible diagnosis of scabies. A skin scraping teeming with mites and eggs confirmed the diagnosis of crusted scabies. To our knowledge, only a few cases of crusted scabies have been reported from our country.

Discussion

Crusted scabies has been defined as a scabies mite-induced psoriasiform dermatosis on the hands and feet with dystrophy of the nails and an erythematous scaling eruption that may be generalized.[1]

In common scabies, there are few mites, probably because scratching destroys the burrows. However, in crusted scabies, lesions are teeming with mites and eggs.[2]

Skin anesthesia occurring in disorders such as leprosy or spinal injury, lack of appreciation of pruritus in Down's syndrome and dementia, physical inability to scratch due to paresis or severe arthropathy, and immune deficiency are predisposing factors for crusted scabies.[1,2,3]

Crusted scabies may masquerade as hyperkeratotic eczema, psoriasis, Darier's disease and contact dermatitis.[2]

The diagnosis is confirmed by examination of scrapings which will be teeming with mites and eggs.[2]

Our patient, who apparently had not any significant disease, lacked several features that are usually seen in crusted scabies. He did not have any palmar, plantar or subungual crusting. He had not head involvement as well. In addition, he had no neurologic abnormalities that prevented the sensation of pruritus.

In conclusion, this peculiar manifestation of crusted scabies, namely crusted scabies without involvement of palms, soles and head and also without subungual crusting or the usual lack of pruritus, can occur in an apparently healthy person. This possibility should be kept in mind in order to prevent misdiagnosis of this uncommon condition.

References

1. Orkin M. and Maibach HL. Scabies and pediculosis. In: Dermatology in general medicine. Freedberg IM, Eisen AZ, Wolffk, etal, eds. 5th edn. Vol. 2. New York: McGraw-Hill. 1999: 2677-2695.

2. Burns DA. Disease casued by arthropods and other noxious animals. In: Textbook of dermatology. Champion RH, Burton JL, Burns DA and Breathnach SM, eds. 6th edn. Vol.2. Oxford: Blackwell Scientific Publications. 1998: 1423-1481.

3. Calnon CD. Crusted scabies. Br J Dermatol 1950; 62: 71-78.

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