A case of non-neoplastic glandular structures embedded in the centre of a bone marrow trephine biopsy is described. This is a hitherto unreported phenomenon. These glandular structures originated from the dermal sweat gland and represented an artefactual lesion produced by the biopsy procedure. The importance of considering the possibility of non-neoplastic glandular structures in bone marrow is stressed, in order to avoid a misdiagnosis of metastatic adenocarcinoma.