Primary Cutaneous CD4+ Small Medium T Cell Lymphoproliferative Disorder – 20 years of experience from a specialist centre

Background Primary Cutaneous CD4+ Small Medium T Cell Lymphoproliferative Disorder (PCSM-TLPD) is a rare subtype of indolent lymphoproliferative disease. The treatment, investigations and follow-up protocol are being re-evaluated. Objective To use our service evaluation to understand the presentation, response rate, relapse rate, treatment variation, progression free and overall survival of our cohort. Methods We identified 86 patients with PCSM-TLPD from our skin tumour unit data base who were diagnosed by the specialist multi-disciplinary team at our centre between 2005 and 2024. As well as demographics and clinical features, overall survival, progression free survival, response to treatment and risk factors for relapse were investigated. Results 86 patients (mean age 54.9 years, range 17-87 years) were included. The majority of PCSM-TLPD lesions presented as solitary nodules (n=75) on the head and neck (n=51). 81 patients underwent imaging (PET: n=44, CT-TAP n=37) with no evidence of nodal or systemic involvement in 100% of cases. 47 patients had a diagnostic biopsy which resulted in spontaneous resolution for 16. 31 had a residual lesion and were treated with topical steroids (n=20) or radiotherapy (n=11). 39 patients had a complete excision followed by monitoring alone for 33 patients. Six had radiotherapy after excision. All patients achieved CR. Patients initially presenting with multiple lesions (n=11) were more likely to relapse (7 of 11 with multiple [63%] vs. 3 of 75 with solitary [4%]) (p<0.001). Three patients died during follow-up from unrelated illnesses. The median follow-up was 3.1 years (1.2 - 4.9 interquartile range [IQR]). The median progression free survival (PFS) was not reached due to insufficient events. The overall relapse rate was 11.6% following initial monitoring or treatment. Disease specific survival is 100% to date. Conclusion PCSM-TLPD carries an excellent prognosis, especially for those presenting with a solitary lesion. There was no disease related death in our patients up to 20 years after presentation. Staging scans confirm no systemic disease and may no longer be required for these patients. Patients can be monitored or treated with low dose radiotherapy (8Gy in 2 fractions) if they do not respond to topical steroids.