PMC6370174_01
Abdominopelvic computed tomography scans indicate the obstruction of the proximal ascending colon with segmental wall thickening. (A) Transverse section. (B) Coronal section.
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F1
As mechanical ileus was suspected, abdominal computed tomography (CT) was performed, which indicated an enhanced obstructive mass 5 x 5 cm in the cecum, and enlargement of the lymph nodes around the mass (Fig. 1).
Gross examination findings of the specimen. A mass 5 x 5 cm in size can be observed at the proximal ascending colon that appears as a submucosal tumor with an intact mucosa.
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F2
However, on visual examination of the specimen, the mucosa was unexpectedly found to be intact, and the mass appeared to have originated from the outside of the lumen (Fig. 2).
Whole body positron emission tomography-computed tomography scans indicate a spiculated ellipsoid solid mass with a hypermetabolic state (standardized uptake value, 11.0) in the right upper lung.
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F3
As the chest CT and PET findings indicated the presence of lung cancer in the right upper lung (Fig. 3), CT-guided needle biopsy was performed, which indicated adenocarcinoma.
Histologic findings. (A) The colon wall shows infiltration of a moderately differentiated adenocarcinoma with no mucosal or submucosal, muscle, and pericolic soft-tissue involvement (hematoxylin and eosin, x10). (B) On immunohistochemical staining, the malignant cells were positive for cytokeratin 7, which suggested that they did not originate from primary colon cancer (x100), and were positive for (C) thyroid transcription factor 1, which suggested that they originated from lung cancer (x100).
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F4
Moreover, immunohistochemical staining indicated positive results for thyroid transcription factor 1 (TTF-1) and cytokeratin 7 (CK7) and negative results for CK20 and CDX-2 (Fig. 4).