Physical exam

Ms. SA was still a very pleasant, well developed, thin Arabic female, aged 22 years, in no acute distress. Her skin is warm and dry with no evidence of open wounds. There were very well demarcated patches on her center chest, bilateral flanks, and center lower back. The patches were slightly papular and erythematous with evidence of scaling. There were no other signs of rash on her body.

A 4mm punch biopsy was taken from the lower back and right flank to determine the histology of the new rash. The result given two weeks later was consistent with psoriasis. She was continued on desoximetasone 0.25%  spray for two weeks.

Incidentally, at the next follow up, the patient also complained of increased itching since her last visit, especially at night, all over her body, but especially her feet. The patient revealed multiple excoriated papules and small fissures on her feet in the web spaces, to which a scabies oil prep slide was performed immediately.

The slide revealed a scabies mite with unexpelled ova. The patient, as well as her family, was treated with 5% permtherin cream two applications one week apart. She was counseled on the proper hygiene and cleaning techniques for her home and family, and asked to follow up in two weeks.

At her follow up, the patient was clear. Her psoriasis was well-controlled using desoximetasone 0.25% spray as needed for active plaques.

Discussion

Confluent and reticulated papillomatosis (CRP) was first described in 1927, by Gougerot and Carteaud. The etiology is unknown, but is thought to be an inappropriate reaction to fungi on the skin.

It usually affects young people and appears as a dusky, sometimes velvety papular rash that coalesces into a plaque on the neck and trunk. The edges of the plaques sometimes appear reticular. The rash can appear hypopigmented in darker Fitzpatrick skin types, which can be misdiagnosed as tinea versicolor.

The rash in this case appeared slightly erythematous and was mistaken for eczema. An oral antibiotic with topical retinoids is usually the treatment of choice, but no therapy has been considered the gold standard.

In the case of Ms. SA, a biopsy confirmed the diagnosis and she was eventually treated with doxycycline, which helped to clear most of her rash, and then later an antifungal was added with complete success. Although CRP does not usually present with pruritus, Ms. SA was treated with topical corticosteroid, as well as an antihistamine for the itch.

There is a genetic predisposition in patients with eczema or atopic dermatitis. These patients have a defect in their adaptive and innate immunity. Their immune response is inappropriately hyper-responsive to environmental stimuli causing the skin barrier to be defective, thus resulting in increased epidermal water loss and a scaly appearance.

This defect in the barrier also makes an atopic patient more susceptible to bacterial and viral infections, increasing the inflammatory response causing the erythema that is most commonly described in eczematous rashes.

Psoriasis can present as thin, scaly, non-descript, erythematous patches and plaques, which can also be misdiagnosed as eczema, but histologically psoriasis is described as a parakeratotic dermatosis versus a spongiotic dermatosis description of eczema. Although both eczema and psoriasis are immune-mediated inflammatory skin disorders, biopsy should be performed to distinguish between the two if there is uncertainty.

An accurate diagnosis of psoriasis is important in patients who may be at risk for arthritic changes. The use of biologics and systemic medications may be necessary early in therapy to prevent damage to the joints. Ms. SA did not have joint pain complaints. Her therapy was strictly topical and was successful.

Scabies is an infestation of microscopic mites, which burrow into the skin laying eggs along the way. A common complaint in a patient with scabies is increased itching at night. Ms. SA had this complaint early in her therapy, however multiple dermatoses also present with nocturnal itch.