Colon, Low grade carcinoma

This patient had a history of low grade colonic carcinoma (this slide), with subsequent distant metastases. During surveillance imaging, a soft tissue mass was found, involving the lower uterine segment and cervix causing distention of the endometrial cavity. A pelvic exam was completed and cervical cytology taken. Cervical cytology revealed groups of disorganized and tightly grouped glandular cells displaying nuclear hyperchromasia, pleomorphism, pseudostratification and overlapping. No nucleoli were identified. No distinct rosetting or feathering was appreciated. A diagnosis of Adenocarcinoma, NOS was rendered.

The differential diagnosis in this scenario includes: endocervical adenocarcinoma, those related to HPV infection as well as those which are not; endometrial carcinoma; and extrauterine carcinomas involving the cervix. Mucinous endocervical adenocarcinomas may be difficult to recognize as they typically show bland nuclear features and high nuclear to cytoplasmic ratios due to abundant cytoplasmic mucin. Goblet cell or gastric foveolar type differentiation may be present. Block expression of p16 may be seen on cell block preparations, however non-HPV associated endocervical adenocarcinomas may be negative for p16. HIK1083, a recently described marker for gastric type mucin, may be helpful in the identification of gastric type endocervical adenocarcinoma. Well differentiated endometrial adenocarcinomas often have vacuolated cytoplasm and may show intracytoplasmic neutrophils; these tumours would be expected to be positive for estrogen receptor with immunohistochemical studies. Extrauterine carcinomas can show a variety of patterns/cell shapes, as well as nuclear and cytoplasmic characteristics, depending on origin.

In this case, PCR evaluation for the detection of HPV DNA was initiated, in addition to the formation of a cell block. The cell block was composed predominantly of benign squamous cells with occasional columnar epithelium arranged in small groups with focal glandular formation. Nuclei were noted to be basally located with some pseudostratification. Abundant intracytoplasmic mucin was seen in these cells.

Immunohistochemistry was performed, and the suspicious columnar cells stained with CK20 and CDX2. In addition, these cells were negative for CK7, p16, HIK1083 and no HPV DNA was detected by PCR. As such, a final diagnosis of metastatic adenocarcinoma consistent with colorectal origin was given.

This slide shows the colonic biopsy. See related content for cell block slides and cytology from subsequent metastatic adenocarcinoma.