PMC6448537_01
Immunohistochemistry demonstrated on vaginal biopsy.. Notes: This combination of stains is highly suggestive of a malignancy of gastrointestinal origin. (A) Moderately differentiated adenocarcinoma on H&E staining at 200x magnification. (B) Positive stain for CK 20 at 200x magnification. (C) Positive stain for CEA at 400x magnification. (D) Positive stain for CDX 2 at 200x magnification.. Abbreviations: CEA, carcinoembryonic antigen; CDX, caudal-related homeobox 2; CK, cytokeratin.
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Histology from the vaginal biopsy showed features of an ulcerated and invasive moderately differentiated adenocarcinoma exhibiting endometrioid architecture (Figure 1A). The immunophenotype was positive for cytokeratin (CK) 20 (Figure 1B), carcinoembryonic antigen (CEA) (Figure 1C), and caudal-related homeobox 2 (Figure 1D), with very minor immunoreactivity for CK 7 and negative staining for estrogen receptor, progesterone receptor, vimentin, thyroid transcription factor 1, a primary lung cancer marker, and gross cystic disease fluid protein (GCDFP15), a breast tumor marker.
PET-CT demonstrating a uterine FDG-avid "hotspot". (A) Coronal plane. (B) Sagittal plane. (C) Transverse plane.. Abbreviations: CT, computerized tomography; PET, proton emission tomography.
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With no obvious primary tumor elucidated from endoscopy/colonoscopy, a proton emission tomography (PET)-CT was organized (Figure 2A-C). Although fibroids may explain the increased uptake, a malignant neoplasm could not be excluded in view of the hotspot that was noted (Figure 2C).