FA is an epithelial tumor whose cells and architecture resemble that of<unk>  lung tissues in the pseudoglandular stage of development (which occurs at about 10–16 weeks gestation in the human), with complex glandular structures and morules with cell nuclei that appear clear due to the accumulation of biotin. While FA can be diagnosed via biopsy, bronchial brushings, and immunocytochemistry, examination of the whole tumor is required to rule out biphasic pulmonary blastoma, a mixed tumor of higher aggressiveness, wherein FA occurs admixed with primitive blastoma cells. Although it is not normally considered a fast-growing malignant neoplasm, FA can exhibit high uptake on FDG-PET scanning. Identification of aberrant nuclear localization of a mutated protein product of the beta-catenin gene has been proposed as a diagnostic tool for FA. Although FA's usually occur as nodules or masses, they can sometimes present as a multifocal disease.
Fetal adenocarcinoma
Placental site trophoblastic tumor
Transgender pregnancy
Fetal rhabdomyoma
Fetus in fetu
Gestational choriocarcinoma
Heterotopic pregnancy
Gestational trophoblastic disease