Occult breast cancer in a female with benign lesions

Occult breast cancer is a carcinoma discovered by the presence of axillary lymph node metastases without the detection of the primary breast tumor. The incidence of this very rare pathology is 0.3%-1.0%. The limited number of these cases does not allow for the precise management of this rare pathology and often, the breast cancer manifestation can take many years to become obvious. We report the case of a 35-year-old woman who presented to our department for annual breast screening examination, without any symptoms. At the time of visit, there were two right and one left tumefactions; unfixed and palpable. Ultrasonography examination confirmed the lesions to be benign. One year later, a palpable hypoechoic axillary left lesion appeared: a lymph node with doubtful morphology. On cytological examination, a biopsy was performed for the axillary left mass which showed irregular masses of large malignant cells with pleomorphism and mitotic figures that suggested a carcinoma. The management of this case is suggestive for cancer of unknown primary syndrome.