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Published on: January 9, 2019
Relationship Between Pityriasis Lichenoides and Mycosis Fungoides: A Clinicopathological, Immunohistochemical, and
Hiba Zaaroura1, Dvora Sahar2, Tova Bick3
1Departments of Dermatology.
Background:
Several cases of pityriasis lichenoides (PL) have been reported to evolve into mycosis fungoides (MF).
Objective:
To elucidate clues to this progression.
Methods:
Fifty-eight patients with PL between 2000 and 2013 (follow-up: 3-16 years, average: 8.3).
Results:
A total of 3 (5.2%) of the 58 patients with PL developed MF after 3-11 years of prolonged clinical course. Papules and small plaques characterized PLs, and patches and larger plaques subsequent MFs. A total of 35 of 41 (85%) followed up non-MF associated patients with PL reported lasting complete remissions. Histopathologically, apoptotic keratinocytes disappeared mostly or completely in subsequent MFs. The presence of epidermotropism, folliculotropism, and epidermal lymphocytic nuclear atypia in PLs was not predictive of MF. CD8 cells were the dominant intraepidermal lymphocytes in the 3 PLs but remained so in only 1 subsequent MF. CD7 lymphocytes decreased substantially in 2 MFs, and lymphocytic nuclear atypia increased markedly in 1. T-cell receptor gene rearrangement studies demonstrated clonal populations in 1 of 2 studied PLs and in all 3 subsequent MFs.
Conclusions:
A few PLs may evolve into MF. Prolonged clinical course, appearance of patches and larger plaques, markedly increased lymphocytic nuclear atypia, marked diminution of apoptotic keratinocytes and CD7 and CD8 lymphocytes, and clonal T-cell receptor gene rearrangement may serve as clues.
Insights
A small percentage of pityriasis lichenoides (PL) cases can progress to mycosis fungoides (MF). Key indicators include a prolonged course, plaque development, and specific cellular and genetic changes.
Area of Science:
- Dermatology
- Oncology
- Pathology
Background:
- Pityriasis lichenoides (PL) is a rare condition.
- Several cases suggest PL can transform into mycosis fungoides (MF).
Observation:
- This study followed 58 patients with PL for 3-16 years.
- The study aimed to identify predictors of PL progression to MF.
Findings:
- 3.2% of PL patients developed MF after a prolonged course.
- Progression to MF was associated with plaque formation, reduced apoptotic keratinocytes, altered CD7/CD8 lymphocyte counts, and clonal T-cell receptor gene rearrangement.
- Most PL patients (85%) did not develop MF and achieved remission.
Implications:
- Identifying early signs of PL transformation to MF is crucial for patient management.
- Specific histopathological and molecular markers may aid in predicting progression.
- Further research is needed to fully understand the PL to MF transition.
