Discussion:
SPTCL is one of the rarest subtypes of non-Hodgkin lymphoma (NHL) in
children, constituting less than 1% of the NHL and the cutaneous
lymphomas (2,3) with limited literature in the pediatric population
(4,5). No definite gender predilection is noticed, but a slight female
predilection is reported by a few studies and is usually associated with
good outcomes (5).
Historically, the SPTCL has two subtypes based on T-cell phenotypes –
alpha/beta (α/β) with better prognosis and gamma/delta (γ/δ) with poor
outcome (3). The European Organization for Research and Treatment of
Cancer (EORTC) classification (2005) modified this categorization and
advocated the use of α/β T-cell phenotype for SPTCL only and described
γ/δ T-cell phenotype as a
distinct cutaneous T-cell lymphoma (6). On immunochemistry, the
malignant T-cells in SPTCL are CD8+ve, CD3+ve, beta-F1+ve, CD4-ve, and
CD56-ve. The γ/δ T-cell phenotype cutaneous T-cell lymphoma is CD56+ve,
while beta-F1-ve, and CD4 and CD8 are negative in most cases (3).
Histopathology with immunohistochemistry is the gold standard for the
diagnosis and is confirmatory in almost all cases (5).
The histological findings include T-cells and macrophages infiltrating
subcutaneous fat lobules with relative sparing of the dermis and
epidermis simulating panniculitis. The malignant T-cell infiltration of
the hypodermic soft tissue in SPTCL incites an inflammatory response
very similar to panniculitis (7,8). The inflammatory change can involve
a single site or be multicentric, presenting as soft tissue nodules,
plaques, edema, discoloration, and itch (5). Compared to young infants,
older children with SPTCL present frequently with fever and weight loss
(90% vs 40%) and have a higher association with HLH (45.5% vs 20%)
(1).
Ultrasound is the initial imaging modality of choice owing to the
superficial location and typically demonstrates vague inflammatory
changes with or without regional lymphadenopathy (9). CT/MRI may help to
determine the extent of inflammatory changes, evaluate deeper
structures, underlying masses, and loco-regional lymphadenopathy (3,10).
FDG-PET is considered the most useful imaging modality, integrating both
anatomical and functional assessment. (11,12). FDG-PET demonstrates the
distribution and uptake of the FDG at the primary site and any
involvement of the distant sites, visceral organs, and lymph nodes,
allowing for accurate pre-treatment staging (3,11). It can also help to
guide the optimal biopsy site based on the metabolic activity and FDG
avidity (12). Post-therapy FDG-PET is useful in determining the
treatment response, degree of residual disease, and any signs of
recurrence (3,11,12).
The management of SPTCL in the pediatric population is variable and
largely depends on the histopathological diagnosis and institutional
preferences. Potential treatment modalities include observation,
immunosuppression, chemotherapy, and radiotherapy (4,13). Similar to the
adults, pediatric case series have shown good treatment outcomes with
dual immunosuppression (cyclosporin-A and prednisolone) in childhood
SPTCL, particularly in the absence of HLH (4). One of the largest
reviews of pediatric PTCL shows the best treatment outcome in SPTCL with
maximum 5-years survival compared to the other pediatric PTCL (14).
Conclusion :
Clinically, the SPTCL often mimics the panniculitis from a benign
dermatological disease; initial imaging and histopathological findings
can also be non-diagnostic and a high index of suspicion is required to
reach an accurate diagnosis. FDG-PET has emerged as an excellent imaging
tool that can provide a road map for the diagnosis and management of the
SPTCL by accurately guiding the biopsy site, eluding false-negative
examinations, and by identifying the multicentricity of the disease. Our
case represents the first case of breast SPTCL in the pediatric
population and describes the role of FDG-PET in the evaluation of the
lesion, determining the multicentricity of the disease, and
loco-regional lymphadenopathy.
Conflict of Interest statement: No affiliations to any
organization.
Acknowledgements : None
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