A clinical and histolopathological study of pityriasis lichenoides

Background: Pityriasis lichenoides is a papulosquamous disorder of unknown etiology with remissions and exacerbations. Histopathology helps greatly in the diagnosis of this condition.
Aim: We studied clinical and histopathological features of pityriasis lichenoides in our patients.
Methods: This is a 3-year retrospective and prospective, descriptive study of all patients clinically diagnosed as pityriasis lichenoides and confirmed by histopathology. All patients were studied clinically and histopathologically.
Results: There were 51 (30 males and 21 females) cases of pityriasis lichenoides in the study period. The maximum number of cases, 14 (27.45%) were in their second decade of life. Pityriasis lichenoides chronica was diagnosed in 39 cases (76.47%) and pityriasis lichenoides et varioliformis acuta (PLEVA) in 12 cases (23.53%). Histopathologically, basal cell vacuolation and perivascular infiltrate were seen in all the cases. Exocytosis was seen in 45.1% of the cases. All the cases of PLEVA showed lymphocytic vasculitis albeit without fibrinoid deposition in the vessel walls.
Conclusion: Pityriasis lichenoides is not a rare disorder. and is not a true lymphocytic vasculitis as blood vessel damage and fibrinoid deposition in the blood vessel walls were not seen in this study.