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

INTRODUCTION: Lymphadenopathy is a common finding in toxoplasmosis. A breast mass due to toxoplasmosis is very rare, and only a few cases have been reported. We present a case of toxoplasmosis that presented as a swelling in the axillary tail of the breast with a palpable axillary lymph node which mimicked breast cancer. CASE PRESENTATION: 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. CONCLUSIONS: Toxoplasmosis rarely presents as a pseudotumor of the breast. FNAC and histology are valuable tools for a diagnosis of toxoplasmosis, and serology is an important adjunct for confirmation.