Clinicopathological Features of Cutaneous Lymphomas and T-Cell Receptor Gamma Gene Rearrangement Studies in Early Stage Mycosis Fungoides

OBJECTIVE: To study the clinicopathological features of cutaneous lymphomas and the role of TCR gene rearrangement in the diagnosis ofpatch/plaque (Stage I/IIA) mycosis fungoides where the histological diagnosis of mycosis fungoides could not be excluded or the diagnosis was suggestive but not confirmatory. METHOD: Ahospital based cross sectional study was conducted from November 2012 to August 2014 where in patients with a diagnosis of cutaneous lymphoma (CL) were included. Diagnosis was established by histology and immunohistochemistry and classified based on WHO-EORTC classification. TCR gamma gene rearrangement assay was done by PCR in patch/plaque (Stage I/IIA) mycosis fungoides (MF) where the histological diagnosis of mycosis fungoides could not be excluded or the diagnosis was suggestive but not confirmatory. Routine laboratory tests; lymph node, bone marrow biopsies and imaging were done when indicated for staging based on the ISCL/EORTC proposal. RESULTS: There were 54 patients (M/F-1.25) with CL.This included primary cutaneous T-cell lymphomas (CTCL) (48), secondary CTCL (4), primary cutaneous B-cell lymphoma (CBCL) (1) and secondary CBCL (1). Among CTCL there were 27 cases of MF, LyP (lymphomatoid papulosis) (8), SPTL (subcutaneous panniculitis like T-cell lymphoma) (6), ALCL (Anaplastic large cell lymphoma) (3), PTCL, NOS (peripheral T-cell lymphoma, not otherwise specified) (3) and HVLL (hydroa vacciniforme like T-cell lymphoma) (1). Mean age at diagnosis of MF, CD30+ LPD, SPTL and PTCL, NOS were 41.1±18.8 years, 33.8±17.1 years, 33.6±17.3 years and 56.3±18.9 years respectively.Paediatric CL accounted for 16.7% of cases. The most common type of CTCL in the paediatric age group (≤20 years) was MF (n=4, 44.4%) followed by LyP (n=2, 22.2%), SPTL (n=2, 22.2%) and HVLL (n=1, 11.1%). Male preponderance was noted in all subtypes of cutaneous lymphoma except SPTL. Unusual clinical types of MF in our study included hypopigmented MF and dyshidrosiform MF. MF with palmoplantar involvement was seen in 14.8% patients. Among the unusual types of CTCL (other than MF) seen in our study were one case each of erythrodermic ALCL, LyP type D and HVLL. Clonality detection rate among early stage MF in our study was 61.5%. Statistical significance of clonal detection with histological grading and immunohistochemistry findings was not found in our study. CONCLUSION: CTCL was the most common subtype as reported in earlier studies from Asian countries and the West. However the proportion of CBCL was lower than that reported from other countries. Female preponderance was noted in SPTL and rest of the subtypes showed a male preponderance.MF was the commonest among CTCL comprising 56.25% of all CTCLs. Monoclonality detection in early stage MF was slightly lower than the detection rate in various studies across Europe using a similar protocol. Though the statistical significance of clonality detection with histopathological grading of MF could not be demonstrated it was evident that in patients with histopathological diagnosis suggestive of MF had increased clonal detection rate.Usefulness of TCR clonal rearrangement studies in early MF has to be further evaluated with large population studies