Cellular Pathology Report of a Colon Cancer Patient

Clinical Scenario

The clinical scenario below will provide you the information to enable you to complete the laboratory report. Completing the report gives you the appreciation of the techniques used in cellular pathology and the final diagnosis for the patient is the put together of all the techniques used.

Gender: F

Age: 79 years old

Clinical details: right hemicolectomy

Right hemicolectomy comprising on ileum measuring 40mm in length and up to 15mm in diameter along with caecum and transverse colon measuring 200mm in length and up to 30mm in diameter. The ileo-caecal mesentery extends up to 90mm from the bowel wall. There is no serosal perforation seen. There is an area (A) measuring 25mm in dimension located 60mm from the proximal (closest right margin). This area appears unremarkable apart from flattened mucosa. There is a nodular area in the submucosa but no residual tumour is identified. The ileocaecal tie is 110mm from area A.

There are 3 more sessile polyps ranging from 5-15mm in the transverse colon, the closest is a 55mm from the distal right margin.

The background mucosa shows possible diverticula.

There are 2 synchronous carcinomas in this specimen, one in the ascending colon and one in the transverse colon. Two separate templates for part reporting are used for each tumour (RCPath guidelines).

Site: ascending colon

Ascending colon tumour is an invasive adenocarcinoma which is present entirely within a lympho-glandular complex (GALT – gut associated lymphoid tissue) in the submucosa. The mucosa overlying the invasive tumour shows sessile serrated lesion with no dysplasia. Site of previously removed polyp cancer is not identified on macroscopic examination but considering that a sessile serrated polyp was present adjacent to previous carcinoma, it is likely that this is a residual tumour from previous polypectomy excised that has herniated in the underlying lympho-glandular complex.

Differentiation - moderate

Local invasion - submucosa (pT1)

Carcinoma involvement of margins – no

Deepest level of lymphatic invasion – none

Site: transverse colon

This is a <10mm diameter invasive adenocarcinoma arising from a 10mm diameter polyp which is a mixed polyp, with one component of sessile serrated lesion and the other, tubular adenoma with high grade dysplasia. Depth of tumour invasion beyond muscularis mucosae is approximately 1mm.

Differentiation - moderate

Local invasion: submucosa (pT1)

Carcinoma involvement of margins – no

Deepest level of lymphatic invasion – submucosal and mucosal lymphovascular invasion present

Total number of nodes – 20

Number of lymph nodes involved – 0

Highest lymph nodes involved – 0

Number of tumour deposits – 0

Histologically confirmed distant metastatic disease – no

Complete resection (by >1mm) at all margins – yes

Stage (TNM 8) – pT1, pN0, pMx (for both ascending and transverse colon)

Ascending colon tumour

MMR - Immunostaining shows loss of MLH1 and PMS2 in the invasive carcinoma.

There is positive nuclear staining with MSH2 and MSH6.

CDX2 is negative.

Transverse colon tumour

MMR - Immunostaining shows loss of MLH1 and PMS2 in the invasive carcinoma.

Positive nuclear staining seen with MSH6 and there is very weak and focal nuclear staining with MSH2 CDX2 is weak positive.

Final diagnosis:

Ascending colon and transverse colon tumours: Right hemicolectomy

Ascending colon – moderate differentiated adenocarcinoma in the lympho-glandular complex.

Transverse colon – moderate differentiated adenocarcinoma arising from a mixed polyp with an adenomatous component showing high grade dysplasia and serrated component.

Stage (TNM 8) – pT1, pN0, pMx (for both ascending and transverse colon) Intramural lymphovascular invasion present in the transverse colon tumour.

The clinical scenario described above is to be used for the report. The report should have a short introduction addressing the importance of using Cellular Pathology in diagnosing pathology in the context of cancer diagnosis. The report needs to address the following questions:

• Discuss the importance of early diagnosis in colorectal cancers. Explain the tumour diagnosed in this scenario and the clinical relevance.

• Discuss the importance of patient identifiers and how many are required for unequivocally identifying a patient and the importance of clinical history when considering techniques in cellular pathology.

• Draw the specimen using the details provide in the macroscopic description and briefly discuss the importance of specimen orientation.

• Discuss the importance of using different templates for reporting tumours (RCPath) using this scenario as an example.

• Discuss the importance of staging and grading a tumour considering the scenario described.

• Discuss the importance of immunocytochemistry in aiding diagnosis and particularly the antibodies used in this scenario.

• Review the literature and consider other tests, techniques (including molecular testing), special stains and antibody-antigen reactions that could be used to aid in the diagnosis and explain why you would use them. If different methods of visualisation other than light microscopy, this should also be included.

Reflection

On reading the clinical scenario what were the first questions that came to your mind? What terminology/topics you felt you were familiar with and others that you struggled to understand?