Follicular Lymphoma of Breast: A Case Report from Pakistan.

Introduction: Breast lymphoma (BL) is a rare breast tumour and accounts for <1% of all breast malignancies. It is further categorised into primary BL and secondary BL. This manuscript presents a case report of a patient diagnosed with secondary BL. Case Description: A 51-year-old female presented in the one-stop breast clinic with 6-month history of having a static and painless left breast lump. Mass was firm, non-tender and 2 cm in size. It was not adherent to skin or muscle and it was present in the upper outer quadrant of the left breast. Mammo-sonography revealed a circumscribed mass of 17 mm in the outer quadrant of the left breast. There were enlarged ipsilateral lymph nodes. Core biopsy suggested atypical lymphoid infiltrates. She underwent wide local excision of breast and axillary nodal mass. The definitive histological diagnosis revealed non-Hodgkin's follicular lymphoma grade 2/3. Staging computed tomography scan features were suggestive of cervical lymphadenopathy. Hence, staging workup proved this to be a case of secondary BL. Practical Implication: The early diagnosis of BL is highly relevant. Its diagnosis is challenging due to non-specific clinical presentation and imaging features. Commonly FL is diagnosed on excisional biopsy or after wide local breast mass excision. Primary and secondary lymphomas, though rare, should be considered in the differential diagnosis of breast malignancies.