[Pseudolymphoma of the skin: ambiguous terminology: a survey among dermatologists and pathologists]

Cutaneous pseudolymphomas (CPL) are diseases that simulate cutaneous lymphomas both clinically and histologically but have a benign course. It can be very difficult, if not impossible, to differentiate pseudolymphoma from lymphoma and there is some semantic ambiguity about the term pseudolymphoma. The aim of this study was to determine the exact meaning attributed to the term pseudolymphoma by a representative sample of French dermatologists and pathologists.

We designed two types of questionnaire, one for dermatologists and the other for pathologists, and sent them out to 274 dermatologists and to 110 pathologists.

We received responses from 122 dermatologists (44.5%) and 64 pathologists (58.1%). In the dermatologist group, 56% consider that CPL is not a clearly defined entity, while 58% consider it a benign disease and only 18% feel that most CPLs are related to a precise cause; 72% of dermatologists perform a routine checkup, 58% initiate treatment and 84% conduct follow-up in the case of CPL. Among pathologists, 61% consider that CPL is not a clearly defined entity, 82% feel that cutaneous pseudolymphoma, cutaneous lymphoid hyperplasia and cutaneous lymphocytoma are the same entity, and 75% consider that CPL are benign; 92% perform routine immunohistochemistry studies and only 26% screen for clonality. Bivariate statistical analysis showed that pathologists consider pseudolymphomas as benign entities frequently than dermatologists (χ(2) test: P=0.02; Fisher's exact test: P=0.01) and that there are more pathologists than dermatologists who see more than four pseudolymphomas per year (χ(2) test: P<0.001; Fisher's exact test: P<0.001). Multivariate analysis clearly identified a tendency among doctors viewing pseudolymphomas as a distinct entity to also consider them benign (Odds Ratio 0.29, CI 97.5% 0.14-0.58), irrespective of speciality or type of practice (hospital practice, private practice or both).

This study demonstrates that, in France, the term pseudolymphoma is an ambiguous notion. We believe that cases in which it is impossible to differentiate pseudolymphoma from cutaneous lymphoma should be referred to as lymphoproliferations of undetermined significance, since more than 50% of physicians consider that the term pseudolymphoma designates a resolutely benign entity.