Subcutaneous panniculitis-like T-cell lymphoma
SPTCL; αβ-SPTCL (since the WHO 2008 reclassification removed the γδ subtype, now reclassified as primary cutaneous γδ T-cell lymphoma)
Subcutaneous panniculitis-like T-cell lymphoma is an indolent primary cutaneous cytotoxic T-cell lymphoma in which neoplastic αβ T cells infiltrate the subcutaneous adipose tissue, producing a clinical and histological picture that closely mimics panniculitis. It is more common in young to middle-aged women and is strongly associated with autoimmune disease (especially systemic lupus erythematosus) and germline HAVCR2 (TIM-3) mutations. The most important complication is haemophagocytic lymphohistiocytosis (HLH), which occurs in 15–20% and dramatically worsens prognosis. The 2008 WHO reclassification removed γδ T-cell lesions from this entity (now primary cutaneous γδ T-cell lymphoma, an aggressive disease) — narrowing SPTCL to the αβ phenotype, which behaves indolently with 5-year overall survival ~80%.
Clinical features
- Multiple deep-seated, tender, erythematous to violaceous subcutaneous nodules and indurated plaques.
- Most common on the lower limbs and trunk; also arms, face.
- Median age 35–40; F:M ~2:1.
- Spontaneously resolving lesions may leave atrophic scars (lipoatrophy).
- B symptoms — fever, weight loss, fatigue — in ~50%.
- Strong association with autoimmune disease, especially SLE and discoid lupus.
- ~20% develop haemophagocytic lymphohistiocytosis (HLH) — fever, cytopenias, hepatosplenomegaly, elevated ferritin and triglycerides — a life-threatening complication.
Differential diagnosis
- Lupus panniculitis (lupus profundus) — closest mimic; both can co-exist; clinically and histologically overlapping. SLE serology, dermal mucin and lymphocytic vasculitis support lupus.
- Erythema nodosum — septal panniculitis, usually shins, no atypia.
- Primary cutaneous γδ T-cell lymphoma — much more aggressive; γδ TCR phenotype; epidermotropism more prominent.
- Other panniculitides — pancreatic, infective, factitial.
Histology & molecular
- Lobular panniculitis-like infiltrate of medium-sized atypical lymphocytes "rimming" individual adipocytes — characteristic feature.
- Karyorrhectic debris, fat necrosis and reactive histiocytes.
- Sparing of the dermis and epidermis.
- Phenotype: CD3+, CD8+, βF1+ (αβ TCR), CD4−, CD56−.
- Cytotoxic markers (TIA-1, granzyme B, perforin) positive.
- Clonal T-cell receptor rearrangement.
- Germline HAVCR2 (TIM-3) mutations in a substantial subset, particularly in patients of East Asian ancestry — predisposes to HLH.
Staging
- CT chest/abdomen/pelvis ± PET-CT — usually negative for systemic involvement at presentation.
- Bone marrow biopsy if cytopenias or HLH features.
- FBC, U&E, LFT, LDH, ferritin, triglycerides, fibrinogen — screen for HLH.
- SLE / autoimmune screen (ANA, anti-dsDNA, complement).
- HAVCR2 (TIM-3) mutation testing where available.
Management
- Indolent localised disease without HLH:
- Systemic corticosteroids (prednisolone 0.5–1 mg/kg/day with slow taper) — first-line.
- Methotrexate, cyclosporine — steroid-sparing alternatives.
- Bexarotene, denileukin diftitox — alternative for refractory disease.
- Multifocal / progressive disease:
- Multi-agent chemotherapy (CHOP, CHOEP) — historically standard.
- Romidepsin, pralatrexate — for relapsed/refractory.
- Allogeneic stem cell transplantation — for selected younger patients with refractory disease.
- Haemophagocytic lymphohistiocytosis (HLH):
- Urgent haematology referral.
- HLH-94 / HLH-2004 protocol (etoposide, dexamethasone, cyclosporine).
- Consider allogeneic transplantation in HLH that does not respond.
- Long-term surveillance for relapse and HLH.
Prognosis
5-year overall survival ~80% for SPTCL without HLH; falls to ~45% with HLH. Adverse features: HLH at presentation, multifocal disease, B symptoms, HAVCR2 mutation. Long-term remission is achievable in many patients with corticosteroid-based therapy.
References
- Willemze R et al. Subcutaneous panniculitis-like T-cell lymphoma — definition, classification and prognostic factors. Blood; 2008.
- Polprasert C et al. Frequent germline mutations of HAVCR2 in subcutaneous panniculitis-like T-cell lymphoma. Blood Adv; 2019.
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