Haematopoietic bone marrow: An uncommon mesodermal derivative in mature teratoma

Ovarian mature cystic teratoma is a common benign neoplastic condition. Pathogenetically, it arises from all three embryonic layers or any combination thereof. Histologically, it appears as disorganised mass of various tissue components. Rarely, these tissues are orchestrated in an orderly fashion to commence organogenesis and simulate a foetus, namely ′homunculus′. However, isolated organic development, particularly of mesodermal derivation, in an otherwise haphazard teratoma is exceptional. Herein, we discuss a case of mature cystic teratoma with multiple foci of haematopoietic bone marrow within its adipocyte-rich Rokitansky protuberance.