Biopsying parapsoriasis: quo vadis? Are morphological stains enough or are ancillary tests needed?

Parapsoriasis represents a group of cutaneous disorders that shows variable clinical aspects somehow resembling to psoriasis, how is reflecting by its name. It was first named by Brocq, in 1902, as an entity with three components: pityriasis lichenoides, small plaque parapsoriasis and large plaque parapsoriasis. Nowadays, under the name of parapsoriasis are included only the last two categories, that are considered disorders characterized by the presence of a mononuclear infiltrate in the dermis, composed of T-cells. Until now, there were not established pathognomonic histopathological features to diagnose parapsoriasis.

The aim of the study was to investigate the epidemiological and morphological data of parapsoriasis cases diagnosed at Emergency City Hospital, Timisoara, Romania for a period of 12 years.

The study had two parts; one was retrospective and another one prospective. For the retrospective part, we searched 210111 patient files recorded in our Pathology Service for a period of 11 years, from January 2002 to December 2012. The slides were searched from the archive and re-read by two individual pathologists. For prospective part of the study, we reviewed 11815 histological slides read between January and June 2013. After inspection of the recorded files, the pathologists noted, were available, the localization and number of the lesions, together with symptoms. The biopsied specimens were initially processed with routine histological technique, the archive slides being stained with Hematoxylin and Eosin. While reading the slides, the pathologists paid attention to the architecture of the epidermis, the presence of epidermotropism and interface dermatitis, type of the dermal infiltrate and its distributions.

In the present study, we emphasized the histopathological aspects of parapsoriasis in order to create a basic line that could help in the establishment of a uniformly accepted definition of parapsoriasis on histopathological grounds.