Ultrastructure of pityriasis rubra pilaris with observations during retinoid (etretinate) treatment

Abstract

The light and electron microscopic structure of pityriasis rubra pilaris (PRP) is described in five patients. Hyperkeratosis, hypergranulosis, keratotic plugs in the follicular openings, acanthosis and focal parakeratosis were observed. A moderate perivascular infiltrate was seen in the upper dermis. Electron microscopy revealed moderately activated keratinocytes, a decreased number of tonofilaments and desmosomes, enlarged intercellular spaces, parakeratosis with lipid-like vacuoles and a large number of keratinosomes. Lymphoid cells were present in the epidermis in moderate numbers. At the dermo-epidermal junction, the basal lamina was focally split, containing gaps. Etretinate therapy produced moderate to marked clinical improvement. The histological picture improved but the typical signs of PRP, including follicular plugging, persisted. Ultrastructurally the cellular activity and the amount of hyperkeratosis and parakeratosis decreased, while increases in keratinosomes, intercellular substance, microvilli and desmosomes were observed during treatment.

(Juvenile) Pityriasis rubra pilaris

“…1,2,25,[93][94][95][96][97][98][99] General nutrition and healthcare should be a common denominator in all children when treating the disease. 1,2,25,[93][94][95][96][97][98][99] General nutrition and healthcare should be a common denominator in all children when treating the disease.…”

“…1,2,25 The benefits of topical vitamin A have also been recorded. 95,101 Etretinate has also been shown to be beneficial at a dosage of 0.5-1 mg / kg / day for 3-5 months. 25,[96][97][98][99][100][101][102][103] Isotretinoin at a dosage of 1-2.2 mg / kg / day for 12-16 weeks has been proven to be beneficial.…”

Pityriasis rubra pilaris

“…Dark adaptation thresholds 16 and liver stores of vitamin A 47 may also be normal. Retinol binding protein (RBP), a carrier protein for vitamin A, may be decreased in patients with PRP, 10 , 48 but is frequently within the normal range 49–53 …”

“…Electron microscopy reveals changes in the epidermis: decreased numbers of tonofilaments and desmosomes, enlarged intercellular spaces, and signs of ultrastructural parakeratosis of the stratum corneum, including lipid‐ like vacuoles, incomplete keratinization, and nuclear remnants 50 , 91 . The corneocytes are fusiform with numerous pits 99 …”

Pityriasis rubra pilaris

“…Während einige Autoren überhaupt keinen Behandlungserfolg fanden [13,14,45] oder sogar eine Exazerbation beobachteten [23,27,38], sehen andere in der kombinierten Anwendung von Bade-PUVA und oralen Glukokortikosteroiden (initial 80 mg/Tag) eine effiziente Behandlungsoption der PRP [28]. Kürzlich wurde von dem erfolgreichen Einsatz der Kombination von UVA1-Phototherapie mit oralem Acitretin als Erhaltungstherapie über 6 Monate (Verringerung der Dosis auf 10 und 20 mg im täglichen Wechsel) berichtet, speziell in Bezug auf die sofortige Erleichterung des Juckreizes und den schnellen Beginn der Abheilung des "Suberythroderms" [25].Die extrakorporale Photochemotherapie stellt eine weitere Therapieoption dar,die bei einer kleinen Anzahl von Patienten erfolgreich angewandt wurde [26].…”