Background: Angioimmunoblastic T-cell lymphoma (AITL) which is recognized in the current world health organization classification as a peripheral T-cell lymphoma of the non-hodgkin lymphomas, comprises about 1% of all lymphomas. The average age at the time of diagnosis of AITL is about 65 years and it is rarely seen in patients under 18 years.

Case report: A 16-year-old boy suffering from fever, weakness, paleness, and axillary lymphadenopathy was referred to Kashan Shahid Beheshti hospital. Laboratory tests showed pancytopenia and elevated LDH. Splenomegaly and normal liver size were also reported by sonographist. Bone marrow aspiration was normal and reactive follicular hyperplasia was reported on the first biopsy of axillary lymph node, but with continuing fever and pancytopenia biopsy of the axillary lymph node was performed again and this time AITL was also reported using the pathological and immunohistochemical evaluation.

Conclusion: AITL, a rare lymphoma under 18 years old, typically manifested by lymphadenopathy, splenomegaly, elevated serum LDH and systemic B-symptoms. One of the most common differential diagnoses of AITL is reactive t-cell infiltrative processes which in some cases pathologists may have difficulty distinguishing between them. The diagnosis was confirmed by immunophenotyping and pathology of the axillary lymph nodes.