Download: Pityriasis rubra pilaris

M 64, generalized erythroderma  including palm and sole.

Biopsy from the  left foot. (5 Figs)

Microscopic findings:

  • Biopsy from non-follicular skin, therefore no follicular plugging.
  • Epidermis shows uniform acanthosis, broad rete ridges, confluent granulosis, hyperkeratosis and parakeratosis.
  • No neutrophilic infiltrates in parakeratotic layer.
  • Dyskeratotic keratinocytes in the epidermis with foci of lymphocytic spongiosis.
  • Mild superficial perivascular chronic inflammation.
  • No suggestion of CTCL, psoriasis or drug reaction.
  • Fig 1. fig-1
  • Fig 2.fig-2
  • Fig 3.fig-3
  • Fig 4.fig-4
  • Fig 5.fig-5

Diagnosis:  Pityriais rubra pilaris

Comment:

Pityriasis rubra pilaris (PRP) is a group of rare skin disorders that present with reddish-orange scaling patches with well defined borders covering the entire body or some parts of the body such as elbows, knees, palms and soles.

The palms and soles are commonly involved and become diffusely thickened and yellowish (palmoplantar keratoderma).

PRP is usually sporadic but may be partially inherited. It occurs in all races with equal sex distribution.

There are several forms of PRP of which most common is classical adult-onset PRP.

Classical adult-onset PRP mostly starts on the head, neck and upper trunk as a solitary red scaly rash. Within a few weeks multiple patches and groups of reddish-orange lesions appear spreading downwards that may cover most of the body (erythroderma).

The palms and soles become thickened and yellow in PRP with painful cracks.

Deba P Sarma, MD, Omaha