A 54 year-old Pacific Islander female presents with a three week history of “itchy bumps” on her legs. Initially she noted the bumps on her right lower leg. Subsequently smaller lesions appeared on her left lower leg and right elbow.
Her past medical history is remarkable for diabetes, hyperlipidemia, hypertension, kidney disease, neuropathy and heart disease. She has been on peritoneal dialysis since 2020. She had her left foot amputated in 2023 and underwent a triple bypass in 2022.
On clinical examination she had multiple hyperkeratotic papules and plaques involving her right lower leg (see below). The lesions were hyperpigmented and many had a central hyperkeratotic cone. A shave biopsy was performed to confirm the diagnosis.
Histology: The epidermis is edematous and the granular layer was not observed. There was significant parakeratosis. There were perivascular and perifollicular inflammatory infiltrates with intrafollicular collections of neutrophils.
What is your diagnosis?
Answer: Acquired perforating folliculitis, also known as Kyrle’s disease (KD). KD was first described in 1916 by an Austrian dermatologist and pathologist Josef Kyrle. Kyrle originally called it “hyperkeratosis follicularis et parafollicularis in cutem penetrans.” The condition is not uncommon and is most often associated with renal failure, diabetes or both. Between 4% and 10% of dialysis patients develop umbilicated dome-shaped papules on the legs, or less often on the trunk, neck, arms or scalp. The lesions are often pruritic (itchy) and later lesions may be confused with prurigo nodularis both clinically and histologically. Other predisposing conditions include: HIV infection, sclerosing cholangitis or other chronic liver diseases, hypothyroidism, hyperparathyroidism, Hodgkin disease, healed areas of herpes zoster and possible associations with biologic agents (gefitinib, infliximab, etanercept, bevacizumab, sorafenib, and natalizumab).
The central hyperkeratotic cone projects into the dermis, so that if it is removed a pitlike depression remains. The papules are usually discrete, however they may coalesce to form circinate plaques. Coalescing verrucous plaques are often seen, especially on the lower extremities. Koebner phenomenon may occur.
Treatment: Acquired perforating dermatosis are thought to be a response to trauma, usually scratching or rubbing in response to the pruritus associated with renal failure. So, maximizing treatment for renal failure is a must. The remaining treatments are varied and with variable results. In the old days ultraviolet treatments such as PUVA or UVB were implemented. Hydration of the skin with soaking tub bath in plan water followed immediately with topical triamcinolone ointment prior to bedtime may be helpful. A variety of other topical and oral agents may be useful, such as retinoic acid, tacalcitol, allopurinol, doxycycline, amitriptyline and isotretinoin.
To learn more about KD and perforating folliculitis click HERE, HERE and HERE.