γδ T-cell-rich variants of pityriasis lichenoides and lymphomatoid papulosis: benign cutaneous disorders to be distinguished from aggressive cutaneous γδ T-cell lymphomas.

BACKGROUND

T cells with a γδ phenotype have been associated with aggressive lymphomas. Yet, inflammatory skin disorders and low-grade lymphoproliferative disorders have rarely been described with a predominant γδ T-cell infiltrate.

OBJECTIVES

To review our experience and determine the clinical relevance of the γδ T-cell phenotype in lymphomatoid papulosis (LyP) and pityriasis lichenoides (PL).

METHODS

A retrospective dermatopathology file review looking for LyP and PL characterized by a γδ T-cell phenotype was performed. Clinical manifestations and course, histological features and molecular data were analyzed.

RESULTS

Six of 16 cases of LyP and four of 23 cases diagnosed as PL during a 5-year period (2009-14) were identified. The median follow-up for the whole group was 16 months (range 3-64), showing an indolent clinical course in all cases.

CONCLUSIONS

The detection of a predominantly γδ T-cell phenotype in papular lymphoid-rich infiltrates in the absence of other lesions is not associated with a clinically aggressive course. γδ T-cell-rich variants of LyP and PL may reflect a spectrum of related conditions. This is a single academic centre retrospective chart review of a relatively small sample.