A 69-year-old woman presented with abdominal pain. At colonoscopy, a depressed lesion
with a central raised nodule, approximately 10 mm in size, was identified in the transverse
colon. Under magnifying narrow-band imaging, the lesion revealed a type IIIB capillary
pattern (capillary pattern classification [1]), and a type VI pit pattern (Kudo’s classification [2]) was detected under magnifying chromoendoscopy using 0.05 % crystal violet staining
([Fig. 1]).
Fig. 1 Endoscopic view showed a depressed lesion in the transverse colon. Magnification with
chromoendoscopy using 0.4 % indigo carmine or 0.05 % crystal violet staining revealed
a type VI pit pattern in the depressed area. a Conventional view. b Narrow-band imaging view. c Chromoscopic view with 0.4 % indigo carmine. d Magnifying view with 0.05 % crystal violet staining.
The endoscopic and clinical diagnosis of this lesion was submucosal colon cancer.
Histologic biopsy evaluation demonstrated a moderately to poorly differentiated adenocarcinoma.
For treatment the patient underwent laparoscopic colectomy.
Histologic examination of the surgical specimen revealed characteristic tumor cells
with eosinophilic cytoplasm arranged in a tubular pattern ([Fig. 2]).
Fig. 2 Microscopic view of the orbital surgical specimen showing invasion of the eosinophilic
tumor cells through the submucosa (right side). An adenocarcinoma component with tubular
structure was also evident (left side) (H & E, orig. mag. × 100).
The tumor cells were cuboid to columnar in shape, with a prominent round nucleolus
within a round nucleus. The tumor cells invaded the submucosa without vascular invasion;
the surgical margins were tumor-free. There was an adenoma component at the peripheral
area of the tumor. A clear border was evident between the adenoma component and the
unusual eosinophilic cells. There was no lymph node metastasis. Immunohistochemically,
tumor cells revealed immunoreactivity for cytokeratin 20, carcinoembryonic antigen
(CEA), and mitochondrial antigen, along with nuclear immunoreactivity for p53 in more
than 50 % of the neoplastic cells ([Fig. 3]).
Fig. 3 Diffuse positive staining of antimitochondrial antibody in the adenocarcinoma (orig.
mag. × 400).
Ki-67 stained positive in 10 % of the neoplastic tumor cells. We diagnosed oncocytic
adenocarcinoma. The patient was disease-free after 2 years.
Except in the thyroid and kidney, neoplasms composed of oncocytic cells are generally
rare. The oncocytic variant of colorectal adenocarcinoma has been reported only twice
[3]
[4], and in both cases it was advanced. In those cases the tumor showed immunoreactivity
for CDX2, CEA, cytokeratin 20, and a low Ki-67 labeling index, which accords with
our case. Additional immunohistochemical analysis for chromogranin A, synaptophysin,
and neuron-specific enolase suggested no endocrine differentiation. Oncocytic features
were reported in a patient who had received preoperative chemoradiotherapy [5]. However, our patient did not receive preoperative chemoradiotherapy. Further, lack
of nuclear pleomorphism and vesicular changes may be distinct from oncocytic features
that develop after chemoradiotherapy. Our case, which shows identical histological
and immunohistochemical features to previous cases, is the first case of early-stage
oncocytic adenocarcinoma to be reported. This case shows that some early oncocytic
adenocarcinomas may present as depressed lesions.
Competing interests: None
Endoscopy_UCTN_Code_CCL_1AD_2AC
