An immunohistochemical study of thanatophoric dysplasia type 1 after fetus autopsy examination.

The current case report presents the postmortem examination findings of a 17-week-old female fetus displaying thanatophoric dysplasia type 1 (TD-1) due to a known fibroblast growth factor receptor 3 (FGFR3) gene mutation. Gross and X-ray examination revealed significant abnormalities, including skeletal malformations with prominent TD-1 femur curvature. Microscopical evaluation indicated inadequate histological growth for the gestational age, with specific organ immaturity noted in multiple hematoxylin and eosin sections from internal organs, bone from epiphyses and diaphyses levels. Immunohistochemical analysis was conducted using specific markers, such as S100, CD34, CD117, glycophorin-C, and myeloperoxidase, to identify various hematopoietic and mesenchymal cell types. Furthermore, this report underscores the often-overlooked aspect of fetal hematopoiesis in cases diagnosed with TD-1, shedding light on the development of hematopoietic cells and their markers in various tissues, with a particular emphasis on the investigation of bone marrow foci in areas with incipient or no apparent ossification. Immunohistochemical identification of hematopoiesis also served as an indirect way to identify areas of incipient or abnormal ossification.