Key Insights On Treating Plantar Psoriasis
This author details the diagnosis and management of a patient who presented with severe cracks and fissures on both heels.
An anxious middle-aged caregiver presented to the clinic complaining of very painful heels. Her limping was not due to the typical heel spur syndrome we see. She had severe cracks and fissures on both of her heels. Her soles had gradually become thicker over the last six months and felt hot and painful to the touch.
She was the primary caregiver for her disabled spouse and seriously ill son. She was unaware of any other family members with a similar condition and had tried cocoa butter and abrasive instruments to reduce the hyperkeratosis. Several deep painful cracks had developed in recent weeks. She denied any significant past medical history.
The patient had a height of 5’2” and weighed 140 lbs for a body mass index (BMI) of 25.63 kg/m2. She was a former smoker and denied taking any medication other than vitamins A and D, magnesium and calcium at simple supplement dosages. Remarkably, the soles were quite warm at 97°F. Sole temperatures can vary individually but generally range between 75 and 80°F when one measures this with an infrared thermometer.
The general examination of the skin revealed opaque, yellow-to-white plaques on the palms and knees as well as the soles. The arms and scalp were otherwise clear. The weightbearing plaques were quite thick with multiple deep fissures that tended to spare the arches and sulci. The toenails were dystrophic and thickened with subungual hyperkeratosis while the fingernails exhibited transverse onycholysis with several longitudinal spikes and superficial pits.
Dermoscopic examination of the right knee plaque found red dots on a homogenous pink background with white scales consistent with psoriasis.
I stained the sole scrapings with chlorazol black E, potassium hydroxide and a dimethylsulfoxide fungal stain. The examination of these scrapings under a light microscope failed to detect segmented branching hyphae. I collected nail clippings and sent them to pathology for examination with periodic acid Schiff and Gomori’s methenamine silver stains. This subsequently revealed hyphae within the nail plate consistent with a dermatophyte infection.
Arriving At The Differential Diagnosis
In order to make a differential diagnosis, it is useful to organize our thinking into four areas. What is our first impression, a mimicking condition, the worst case scenario and finally, one esoteric disease?
In this case, considering the opaque keratin, palmar plantar hyperkeratosis and significant stress history, psoriasis was the first impression. A mimicking condition might be atopic eczema but the history and distribution fail to support that diagnosis. The worst case scenario could be a paraneoplastic disorder like Bazex syndrome, which is an erythrosquamous eruption of the fingers and toes associated with lung cancer. Hopefully, a good review of systems would help to rule this out.