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73-Year-Old Female with Diffuse Rash

Can you diagnose this case?

Tokunbo Ajayi, MDSeries Editor

Signs and Symptoms

A 73-year-old white female was becoming increasingly forgetful, reclusive, and had declining medical care in the past year. She presented with confusion, and her daughter-in-law said she was pulling out her hair, scratching, and itching all of her skin for approximately 1 year.

On examination, there were well-demarcated, thin erythematous plaques in the inguinal and axillary regions. The skin surface was smooth, atrophic, non-scaly, and slightly shiny. She also had pitting of the fingernails. The rest of the physical examination was unremarkable.

What’s your diagnosis?

Choose one to reveal diagnosis and discussion

Lice infestation
Lichen planus
Discoid lupus erythematous

ANSWER: Lice infestation

See the full case at Consultant360


A 73-year-old white female was becoming increasingly forgetful and reclusive, and had declining medical care over the past year. She presented with confusion, and her daughter-in-law said she’d been pulling out her hair, scratching and itching all of her skin for approximately 1 year. Physical exam showed linear excoriations marks with post-inflammatory hyperpigmentation, honey-like crusting, and redness around the lesions on her back, trunk, and upper and lower extremities sparing her face. There is non-scarring alopecia with associated excoriation in the middle of her head with surrounding erythema.


Based on history, physical examination and direct visualization of lice’s, the patient was given a diagnosis of pediculosis. Differential diagnoses included: Dermatitis/eczema, Scabies, Discoid lupus erythematous, Psoriasis, Lichen planus, Delusions of parasitosis, and Impetigo


Pediculosis is a disorder caused by infestation by one of any of the 3 types of lice that specifically infest humans: pediculus humanus humanus, pediculus humanus pubis, pediculus humanus capitis. Predisposing factors include poverty, crowding, homelessness, and a low level of personal hygiene. Pediculosis is commonly seen at day care centers, schools, homeless shelters, and prision.

Differentiating louse infestation from scabies can be a little tricky, as they can co-exist. However, in scabies, there is scabetic burrows in the web spaces of the finger, around the genitals, and the wrist. Also, mites of scabies are much smaller than lice, and are undetectable on examination with the naked eye. Delusion of parasitosis is another consideration if the lice mites were not visualized, especially in patients with a psychiatric illness such as schizophrenia.


Itching is a common presenting complaint. Linear excoriations with post-inflammatory hyperpigmentation (licenification), the honey-like crusting (impetiginazation), and redness characteristic of staphylococcus infection, can also be seen on exam. Diagnosis is usually made by visualization of the lice mite or nymph.


Lice serves as a vector for disease entities such as epidemic typhus, trench fever, and relapsing fever. Bartonella quintana transmission via louse infestation can also cause endocarditis.


Adult treatment of pediculosis corporis involves discarding, laundering (in hot water), or ironing infested clothing and bedding. Failure to eradicate or severe cases requires treatment with permethrin 5% cream. Patient was decontaminated in the decontamnating chamber, treated with permetrin cream, shampoo and tetanus-diphtheria toxoid injection. She was treated with mild topical corticosteroids for few days. She was discharged with social worker/elder services due to concern for elderly neglect.

Outcome of the case

Patient’s itching had resolved completely and her skin lesion was better in appearance at follow-up with new primary care physician.


    1. Stone SP, Goldfarb JN, Bacelieri RE. Scabies, other mites, and pediculosis. In: Wolf K, Goldsmith LA, Katz SI, et al, eds. Fitzpatrick’s Dermatology in General Medicine. 7th ed. New York, NY: McGraw Hill; 2008:2029.
    2. Raoult D, Roux V. The body louse as a vector of reemerging human diseases. Clin Infect Dis. 1999;29(4):888-911.