OA14 Subcutaneous panniculitis-like T-cell lymphoma: a mimic of lupus erythematous panniculitis
Authors: Li Danning 
Published: April 2024

Abstract

Background/Aims
Lupus erythematosus panniculitis (LEP) is a rare variant of cutaneous lupus erythematosus characterised by tender, erythematous subcutaneous nodules or plaques on the face, trunk and proximal extremities. Without treatment, profound lipoatrophy frequently occurs, which often has a devastating psychosocial impact. Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare form of cutaneous T-cell lymphoma, which may appear in a similar manner. SPTCL initially preferentially infiltrates the subcutaneous adipose tissue and symptoms vary widely depending on the stage of the disease. Early-stage disease presents as painless self-resolving subcutaneous nodules on limbs and trunk.

Methods
We present the case of a young woman who presented with progressively developing, widespread painful cutaneous lesions, pyrexia of unknown origin and general malaise for one month. She had a history of hurthle cell neoplasm and a strong family history of malignancy. Initial examination revealed 1-2 cm firm, skin-coloured subcutaneous nodules over her lower back, chest and thigh, with groin and axillary lymphadenopathy. Further lesions progressively developed over a three-month period, with lesions turning increasingly erythematous and with associated ulceration. Of note, a significant periorbital lesion appeared, associated with an ipsilateral facial palsy.

Results
Initial bloods revealed an elevated LDH with cholestatic liver function tests. PET-CT imaging showed an enlarged axillary node with extensive pathology throughout the subcutaneous fat of unknown aetiology. Due to the family history, underlying haematological malignancy and atypical Sweet’s were considered for this unusual presentation. Seropositivity for anti-Ro and ENA, alongside raised angiotensin converting enzyme, broadened the differentials to include LEP, mixed atypical connective tissue disease and cutaneous sarcoid. Notably, complement, myositis panel and creatine kinase were normal. Lupus vulgaris was considered due to high local prevalence and excluded with T-SPOT testing. Histopathological analysis of lesional skin from the upper arm found predominantly subcutaneous infiltrates of atypical lymphoid cells with irregular hyperchromatic nuclei and rimming of individual fat cells. T-cell clonality analysis detected clonal T-cell receptor beta (V-J and D-J) gene rearrangements consistent with SPTCL. Her orbital and cutaneous lesions responded well to six cycles of CHOEP (cyclophosphamide, hydroxydaunorubicin, oncovin, etoposide, prednisone) and the patient returned to functional baseline.

Conclusion
This case demonstrates the diagnostic difficulties when managing a patient with relapsing remitting panniculitis. Whilst the initial presentation of SPTCL here was classical, with widespread multifocal subcutaneous nodules, the appearance of facial symptoms in SPTCL is rare. Diagnostic uncertainty is frequent in both LEP and SPTCL due to the initial non-specific cutaneous presentation. This case emphasises the importance of clinicopathological correlation for accurate diagnosis. Interestingly, up to 20% of SPTCL patients have concomitant autoimmune diseases, and there is evidence suggesting a potential association between LEP and subcutaneous SPTCL beyond chance, leading some researchers to propose that these two entities exist along a spectrum.

Disclosure
D. Li: None. L. Spencer: None.