FROM THYROITIS TO LYMPHOMA: A DIAGNOSTIC JOURNEY

Abstract

Intro: Primary thyroid lymphoma is an exceedingly rare entity, accounting for less
than 5% of thyroid malignancies and approximately 2% of extranodal lymphomas,
with an estimated incidence of 2 cases per million annually.More common in women
with 6to 7th decade.Hashimoto thyroiditis is known risk factor.FNAB& biopsy are
crucial.
Presentation of case: A 65-year-old male presented with 10-year history of
progressively enlarging neck swelling,without associated compressive symptoms.
Clinically,the patient was diagnosed with solitary thyroid nodule(Grade 3). USG
neck revealed TIRADS 4 nodule in left lobe and TIRADS 1 nodules in right lobe.
FNAB indicated autoimmune thyroiditis(BethesdaCategory 2).Subsequently, the
patient underwent total thyroidectomy, the specimen submitted for histopathological
evaluation. Macroscopically, the thyroid specimen consisted of left lobe measuring
7.5x5x4.5cm and right lobe with isthmus measuring 4x3x2cm. Microscopic
examination features consistent with thyroid lymphoma in the context of
autoimmune thyroiditis. IHC revealed CD20 and BCL2 positivity(30% of tumor
cells),while CD3, TTF1, CD10, MUM1, and BCL6 were negative. The Ki67
proliferation index 90%. Based on these findings,final diagnosis of diffuse large Bcell lymphoma (DLBCL) of the thyroid with underlying autoimmune thyroiditis was
established.
Discussion: Primary thyroid lymphoma arising from autoimmune thyroiditis,
especially in male patients,is exceptionally rare. Among the various subtypes of
thyroid lymphoma, diffuse large B-cell lymphoma is the most common.
Immunohistochemical findings in these cases mirror those of conventional DLBCL.
Conclusion: Primary thyroid lymphoma is a rare and challenging diagnosis to
establish preoperatively. Once diagnosed, accurate staging is critical for determining
the most appropriate treatment strategy.