Invasive lobular carcinoma (ILC) is a common subtype of breast cancer diagnoses, accounting for up to 15% of breast cancer cases. Occult breast cancer (OBC) is a rarer subset, accounting for 0.1-1% of cases and usually manifest as axillary lymph node metastases from a malignant primary breast carcinoma in the absence of a clinically or radiologically assessable breast mass. This case report provides a unique insight into a patient with an occult primary invasive lobular carcinoma with solitary metastases to the ipsilateral pectoral muscle, without features of axillary lymph node involvement or distant metastatic spread. This case also reiterates the challenges faced when managing occult breast cancers. 

To be updated.