Toxoplasmosis presenting as a swelling in the axillary tail of the breast and a palpable axillary lymph node mimicking malignancy: a case report

A 45-year-old otherwise healthy Caucasian woman presented with a lump on the lateral aspect of her left breast. Her mother had breast cancer that was diagnosed at the age of 66 years. During an examination, we discovered that our patient had a discrete, firm lump in the axillary tail of her left breast and an enlarged, palpable lymph node in her left axilla. Her right breast and axilla were normal. The clinical diagnosis was malignancy in the left breast. Ultrasound and mammographic examinations of her breast suggested a pathological process but were not conclusive. She had targeted fine-needle aspiration cytology (FNAC) and core biopsy of the lesions. FNAC was indeterminate (C3) but suggested a possibility of toxoplasmosis. The core biopsy was not suggestive of malignancy but showed granulomatous inflammation. She had a wide local excision of the breast lump and an axillary lymph node biopsy. Histopathology and immunohistochemical studies excluded carcinoma or lymphoma but suggested the possibility of intramammary and axillary toxoplasmic lymphadenopathy. The results of Toxoplasma gondii IgM and IgG serology tests were positive, supporting a diagnosis of toxoplasmosis.