Cutaneous T-Cell Lymphoma

Nayela Keen, MD

Christine M. Glastonbury, MBBS

Key Facts

Terminology

Cutaneous T-cell lymphoma (CTCL)
Uncommon group and spectrum of lymphomas arising in skin
80% of cutaneous lymphomas are T cell; most are mycosis fungoides (MF)

Imaging

Skin plaques and tumors evident on CECT/MR/PET
Evaluate for enlarged, abnormally enhancing nodes
CT/MR/PET may not be able to distinguish reactive from involved nodes
Very high nodal SUV concerning for transformation

Top Differential Diagnoses

Benign dermatosis
Drug reaction
Idiopathic erythroderma

Pathology

Mycosis fungoides and Sézary syndrome (SS) have own ISCL/EORTC classification system

Clinical Issues

Many variants of CTCL defined by pathologic and serum criteria with variable prognoses
MF confined to skin is chronic indolent disease, normal survival
- Characterized by skin patches, plaques, and tumors
- Poorer prognosis if skin tumors, extracutaneous spread, > 60 years of age, ↑ LDH
SS is leukemic variant with very poor prognosis, 10-20% 5-year survival

Diagnostic Checklist

Imaging has no role in diagnosis, used for staging
Look for nodal and visceral disease

Figure 1 (Left) A 20-year-old male with adenopathy and diffuse skin rash shown to be CTCL on punch biopsy. Peripheral blood smear showed atypical lymphocytes as well. Axial CECT image demonstrates multiple small nodes in neck

and the impression of subtle hazy thickening of the cutaneous tissues

. (Right) Axial CECT more inferiorly in the same patient shows additional small enhancing nodes

and diffuse thickening of the skin

. This patient was clinically determined to have Sézary syndrome.

Figure 2 (Left) Axial PET image in the same patient shows FDG uptake in the small nodes

and an overall impression of increased FDG avidity in the skin

. This mimics what can be seen in nonattenuation-corrected images and is a described PET finding of Sézary syndrome. (Right) Coronal fused PET/CT in the same patient reveals nodal uptake

and better illustrates subtle but diffuse FDG uptake in skin

. Nodal uptake may be reactive (dermatopathic lymphadenopathy) and is not necessarily malignant.

TERMINOLOGY

Abbreviations

Cutaneous T-cell lymphoma (CTCL)

Synonyms

Mycosis fungoides (MF)
Sézary syndrome (SS)
Cutaneous CD30(+) T-cell lymphoproliferative disorder (CC-TCLPD)
- Cutaneous anaplastic large cell lymphoma (C-ALCL)
- Lymphomatoid papulosis (LyP)
Cutaneous peripheral T-cell lymphoma (C-PTCL)

Definitions

Uncommon group of extranodal T-cell lymphomas arising in skin
- 80% of cutaneous lymphomas are T-cell
- ≥ 50% mycosis fungoides, 30% CC-TCLPD, < 5% SS

IMAGING

General Features

Best diagnostic clue
- Multiple, diffusely distributed skin lesions ± lymphadenopathy
Location
- 70% CTCL have cutaneous and nodal lesions in H&N
- Folliculotropic MF has particular predilection for involvement of head and neck
  - Abnormal T-cells infiltrate hair follicles → alopecia
Morphology
- Variable: Plaques (not evident on imaging) to thickened patches to tumor masses > 1 cm