DRESS syndrome is far more common than AITL. Similarities in their clinical presentation pose a substantial challenge and often cause a delay in the diagnosis of AITL, which is made by excisional tissue biopsy, most commonly of a lymph node, with assessment of morphology and immunophenotyping. Histologic assessment of tissue reveals a polymorphous infiltrate of variably sized atypical lymphocytes with prominent arborizing HEVs as well as expanded populations of follicular dendritic cells that can be detected by CD21 staining. Cells express CD3 and CD4, variably express BCL6 (B-cell lymphoma 6 antigen) and CD10, and also may have partial or complete loss of expression of a subset of pan T-cell antigens (CD2, CD3, CD5, and CD7).12-18
The treatment approach to AITL mirrors that of other nodal peripheral T-cell lymphomas, including chemotherapy and consideration of autologous stem-cell transplantation. Recent prospective trials of CHOP and CHOP-like chemotherapy have reported 3-year event-free survival and overall survival rates of 50% and 68%, respectively.19 Novel chemotherapeutic targets and gene-expression profiling are being investigated as potential therapeutic avenues.20
Conclusion
DRESS syndrome and AITL can have near-identical presentations. Clinicians should maintain a high index of suspicion for AITL in patients with presumed DRESS syndrome whose rash does not improve with appropriate drug withdrawal and steroid therapy or who lack a strong offending medication history. In such cases, skin and lymph node biopsies should be performed as early as possible to evaluate for AITL and so that appropriate therapy can be initiated.