case_images: PMC11798423_01
case_images: Ultrasonography of the abdomen and pelvis showing A) 23.1x15.5x22.0 cm complex multiloculated cystic lesion (yellow arrowheads) with a thick outer wall (purple arrow) and B) multiple internal septations (green arrow).
case_images: cureus-0017-00000077013-i01.jpg
case_images: PMC11798423_01_cureus-0017-00000077013-i01.jpg
case_images: FIG1
case_images: The lesion originated in the pelvis and extended to the epigastrium (Figure 1A and Figure 1B).
case_images: A) Gross section of the specimen showing multiloculations with a large locule containing cheesy material and hair (arrow); B) histopathological examination with hematoxylin and eosin stain of the largest locule showing mature cystic teratoma (dermoid cyst) lined by skin and adnexa, original magnification x40; C) sections from tan-white fleshy solid areas displaying a carcinoid tumor with cell arrangement in both pseudoacinar and trabecular patterns on hematoxylin and eosin stain, original magnification x200; D) extracellular mucinous pool with floating islands of carcinoid cells and small round glands lined by cuboidal epithelium as seen with hematoxylin and eosin stain, original magnification x40.
case_images: cureus-0017-00000077013-i02.jpg
case_images: PMC11798423_01_cureus-0017-00000077013-i02.jpg
case_images: FIG2
case_images: Serial sectioning displayed multiloculations, including a large locule containing cheesy material and hair (Figure 2A). Histopathological examination confirmed the largest locule as a mature cystic teratoma (dermoid cyst), characterized by the presence of skin and adnexal structures (Figure 2B). Sections from the tan-white fleshy solid area revealed a carcinoid tumor, exhibiting pseudoacinar and trabecular patterns (Figure 2C). Areas of extracellular mucinous pooling were noted, with floating islands of carcinoid cells and small round glands lined by columnar epithelium (Figure 2D).
case_images: A,B: Synaptophysin and chromogranin immunohistochemical markers showing diffuse staining in the cells of carcinoid component (red arrow) and are negative in the areas of teratoma component (green arrow), original magnification A: x40, B: x100; C: The CDX2 immunohistochemical marker showing positive result for the mucinous component of teratoma (green arrow), and consistently negative result for the trabecular component of carcinoid (red arrow), original magnification x40; D: The Ki67 index is less than 1% favoring the diagnosis of a primary carcinoid tumor, original magnification x200.
case_images: cureus-0017-00000077013-i03.jpg
case_images: PMC11798423_01_cureus-0017-00000077013-i03.jpg
case_images: FIG3
case_images: Immunohistochemical staining with synaptophysin and chromogranin demonstrated diffuse positivity in the typical carcinoid tumor cells (Figures 3A, 3B). The CDX2 marker was positive in the mucinous component but negative in the trabecular component (Figure 3C). Furthermore, the Ki67 index was <1%, indicating a primary origin of the carcinoid tumor rather than metastasis (Figure 3D).