Primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder

PCSM-LPD; primary cutaneous CD4+ small / medium T-cell pleomorphic lymphoma (former WHO 2008 designation); cutaneous "pseudolymphoma with monoclonality" overlap

Primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder is an indolent T-cell entity that the WHO-EORTC 2018 classification deliberately reclassified from "lymphoma" to "lymphoproliferative disorder" (LPD), a framing retained in WHO-HAEM5 (5th edition, 2022) and ICC 2022 — to recognise that, despite a clonal CD4+ T-cell infiltrate that may appear histologically alarming, the clinical course is benign, with solitary lesions that respond completely to local treatment and an excellent prognosis equivalent to a benign condition. The classical presentation is a solitary, slow-growing, asymptomatic, well-circumscribed plaque or nodule on the head, neck or upper trunk of a middle-aged adult. Excisional biopsy or local radiotherapy is curative in the majority. The principal diagnostic challenge is distinguishing PCSM-LPD from cutaneous pseudolymphoma at the benign end and from systemic peripheral T-cell lymphoma with secondary skin involvement at the malignant end — accurate diagnosis requires a cutaneous lymphoma MDT.

CurrentLast reviewed 26 April 2026

Clinical features

Solitary (~90%) slow-growing skin-coloured to red papule, plaque or nodule, typically 1–4 cm.
Site predilection — head and neck (face, scalp), upper trunk; less often arms.
Median age 50; both sexes; immunocompetent patients typically.
Asymptomatic; no B symptoms.
No spontaneous regression (unlike lymphomatoid papulosis), but response to treatment is excellent.
Differential: cutaneous pseudolymphoma (similar appearance and overlap; clonality testing helps), other primary cutaneous lymphomas, systemic peripheral T-cell lymphoma involving skin.

Histology & immunophenotype

Dense, nodular to diffuse dermal infiltrate of small to medium pleomorphic lymphocytes, sparing the epidermis (no epidermotropism).
Background of reactive small B cells, plasma cells, eosinophils and histiocytes.
Phenotype:
- CD3+, CD4+, CD8−, βF1+
- PD-1, BCL6, ICOS positive — supporting follicular T-helper (TFH) lineage in many cases
- CD30 negative or focally weak (distinguishes from CD30+ LPD)
- Ki-67 typically <30%
Clonal T-cell receptor β rearrangement.
Differential by histology: cutaneous pseudolymphoma (polyclonal), pcALCL (CD30+, larger cells), CTCL with secondary nodule formation (epidermotropism, patch/plaque history).

Diagnostic criteria (WHO-HAEM5 / ICC 2022)

Solitary lesion (or very few) — multifocal disease excludes the diagnosis.
Predominant CD4+ T-cell infiltrate, small / medium pleomorphic.
No epidermotropism.
No CTCL history.
No systemic T-cell lymphoma on staging.
Generally indolent clinical course.

Management

Confirm absence of systemic disease — CT chest/abdomen/pelvis (PET-CT optional).
Excisional surgery for solitary lesion — curative in most.
Local radiotherapy (low-dose involved-field RT) — alternative.
Intralesional steroids in selected cases.
Refer to cutaneous lymphoma MDT.
No need for systemic chemotherapy or aggressive treatment.

Prognosis

Excellent — 5-year overall survival >95%, equivalent to a benign condition. Recurrence at the same site is uncommon. Long-term surveillance (annual clinical review) is sensible to confirm absence of new lesions or systemic transformation, but the disease behaves benignly in the great majority of patients.

References

Beltraminelli H et al. Primary cutaneous CD4+ small / medium pleomorphic T-cell lymphoma — clinicopathological study. J Cutan Pathol; 2010.

Willemze R et al. The 2018 update of the WHO-EORTC classification for primary cutaneous lymphomas. Blood; 2019.

WHO Classification of Haematolymphoid Tumours, 5th edition (WHO-HAEM5); 2022. International Consensus Classification of Mature Lymphoid Neoplasms; 2022.