Pruritic and dyskeratotic dermatosis
PDD typically presents as widespread, brown to gray, scaly, velvety, or lichenified papules and plaques. Reported areas of involvement include the neck, back, chest, axillae, buttocks, and/or extremities. PDD notably spares the face. PDD is often severely pruritic, resulting in sleep disruption.
Most patients with clinically confirmed PDD are solid organ transplant recipients on chronic immunosuppression who developed the condition years after successful transplant. Additional cases have been described in patients with HIV infection and one with undiagnosed but suspected underlying immunosuppression. Most patients with PDD present chronically with progressive worsening of rash and pruritus without treatment, although a single case of sustained resolution without treatment has been reported in one patient.
HPyV6 and HPyV7 are believed to be common latent viral infections of the skin in the general healthy population. The pathomechanisms of PDD are currently unknown. However, it is hypothesized to be related to viral upregulation of oncogenes in the setting of immunosuppression that results in disorganized and hyperproliferative growth of keratinocytes. Of note, most of the reported solid organ transplant recipients who developed PDD were receiving rapamycin. The significance of this is currently unknown, and further study is needed to clarify how rapamycin affects replication of HPyV6 and HPyV7.
B09 – Unspecified viral infection characterized by skin and mucous membrane lesions
5714002 – Disease caused by Polyomavirus
64144002 – Pruritic rash
Differential Diagnosis & Pitfalls
- Trichodysplasia spinulosa – many overlapping clinical and histological features; best differentiated with testing for different polyomaviruses
- Exanthematous drug eruption
- Lichenoid drug eruption
- Eczematous drug eruption
- Drug-induced pigmentation
- Chronic graft-versus-host disease
- Atopic dermatitis
- Nummular dermatitis
- Lichen planus
- Lichen simplex chronicus
- Bullous congenital ichthyosiform erythroderma
- Non-bullous congenital ichthyosiform erythroderma