Endometrioid adenocarcinoma with sacral metastasis.

Most bone tumors are metastatic. Breasts, lungs, kidneys, and thyroid are the primary sites most commonly involved in bone metastasis-type outcomes. This case study describes the involvement of a patient with a bone tumor located in the axial skeleton, initially in the sacral region. However, the primary site was undefined. Therefore, it was necessary to expand the investigation with immunohistochemistry, which demonstrated a metastatic tumor compatible with endometrioid adenocarcinoma. But even after examination, no active lesion was found in the endometrial region. The study was observational, descriptive, and aimed to discuss the importance of more specific investigative methods. In this context, immunohistochemistry stands out as an exquisite method capable of optimizing diagnosis, therapy, and consequently, prognosis.