Hypopigmented lesions in pityriasis lichenoides chronica patients: Are they only post‐inflammatory hypopigmentation?

Abstract

Background/Objectives: Pityriasis lichenoides chronica (PLC) lesions are reported to subside with post-inflammatory hypopigmentation (PIH); hence, the most widely perceived nature of hypopigmented macules in PLC is PIH. However, to the best of our knowledge, no studies describing histopathological findings in these lesions are reported in literature. The aim of this study is to evaluate the hypopigmented lesions encountered in PLC patients and to shed light on their histopathological features. Methods:A cross-sectional observational study included twenty-one patients with PLC recruited in a period of twelve months. Clinical characteristics of each patient were collected. A skin biopsy from hypopigmented lesions whenever present was taken and assessed with routine haematoxylin and eosin stain.Results: Seventeen patients (81%) were less than 13 years old. Most patients (85.7%) demonstrated diffuse distribution of lesions. Hypopigmented lesions were present on the face in 12 (57.14%) patients. Histopathologically, hypopigmented lesions showed features of post-inflammatory hypopigmentation in 19% of patients, residual PLC in 52.4% and active PLC 28.6% of patients. Conclusion:Hypopigmented lesions in PLC were noted mainly in younger ages, histopathologically they may show features of active or residual disease, beyond post-inflammatory hypopigmentation. Consequently active treatment for patients presenting predominantly with hypopigmented lesions could be required to control the disease.

Chronic and Stubborn Leuco-melanoderma in a Child: A Case Study

“…Dermoscopy of the leucomelanodermic form has not been described in the literature and in the case of our patient was not of diagnostic help. According to the study conducted by Elbendary et al in 2022, the average duration of depigmentation in the absence of primary lesions is 35 to 20 months for patients with PLC [6]; this duration is longer in patients with a dark phototype [7] confirming the data of the study carried out on PLC in black patients in 2010. This suggests that long-lasting pigmentary change in the absence of apparent primary lesions may represent ongoing disease activity rather than a scarring reaction [8].…”

Basement membrane thickness helps to differentiate hypopigmented mycosis fungoides from clinical and pathological mimickers

“…Pityriasis lichenoides chronica is also one of the diseases that can cause a lot of confusion with HMF as it can present with hypopigmented macules and patches affecting the trunk and extremities of children and young adults with dark skin type 13 . Furthermore, hypopigmented lesions seen in PLC have been found to represent an active or residual disease that shows vacuolar interface dermatitis along with variable degrees of spongiosis, keratinocyte necrosis, and lymphocyte exocytosis 14 . The presence of lymphoid atypia, Pautrier's‐like microabscesses, and wiry fibroplasia in some lesions, 15 and the inability of immunohistochemical and molecular studies to differentiate between PLC and HMF 16,17 can lead to a diagnostic dilemma.…”

“…13 Furthermore, hypopigmented lesions seen in PLC have been found to represent an active or residual disease that shows vacuolar interface dermatitis along with variable degrees of spongiosis, keratinocyte necrosis, and lymphocyte exocytosis. 14 The presence of lymphoid atypia, Pautrier's-like microabscesses, and wiry fibroplasia in some lesions, 15 and the inability of immunohistochemical and molecular studies to differentiate between PLC and HMF 16,17 can lead to a diagnostic dilemma.…”