Clear cell change in colonic tubular adenoma and corresponding colonic clear cell adenocarcinoma is associated with an altered mucin core protein profile

Colonic de novo Clear Cell Adenocarcinoma of Intestinal-Type: A Case Report and Review of the Literature

Colorectal clear cell adenocarcinomas are rare tumors. They can be divided into two types: intestinal- and Müllerian-type. Most intestinal-type clear cell adenocarcinomas show a composite morphology, and most early-stage (T1) intestinal-type clear cell adenocarcinomas have an adenoma component. We report an additional early-stage (T1) colonic clear cell adenocarcinoma that was a de novo adenocarcinoma without any adenoma component. It had a pure morphology and the smallest size (0.6 cm) ever reported. Immunohistochemical results demonstrated an intestinal phenotype (KRT20+, KRT7-, CEA+, and CDX2+). Periodic acid-schiff and alcian blue stains were both negative, which demonstrated decrease in mucin expression in the clear tumor cells. Enteroblastic differentiation was observed in a few colorectal clear cell adenocarcinomas in the literature, while it had not been observed in the present tumor. The tumor did not have deep submucosal invasion and cancer embolus, endoscopic submucosal dissection with regular follow-up was an appropriate treatment for the patient. Due to the rarity and diversity of primary colorectal clear cell adenocarcinomas, the cause of clear cytoplasm change and the impact on patient prognosis remain unknown. Accumulating evidence indicates that clear cell adenocarcinomas of intestinal-type is a histological variant of colorectal adenocarcinoma.

Colonic Tubular Adenoma with Clear Cell Change: Case Report with Whole-Exome Sequencing and Updated Review of the Literature

INTRODUCTION

Colorectal tubular adenomas displaying clear cell change are rare entities, with unknown clinical relevance, prognosis, immunohistochemical, and molecular features.

CASE PRESENTATION

Hereby we report a case of a 43-year-old female patient with a rectosigmoid polyp. Histologically, conventional dysplasia was visible with scattered areas displaying clear cell change. Whole-exome sequencing (WES) was carried out and revealed high tumour mutation burden and 7 pathogenic mutations, including TP53, APC, FGFR4, EHBP1, IL4R, TYR, and ACTN3.

CONCLUSION

Clear cell change may only be present in less than 0.1% of adenomas. Aetiology is not well understood; additionally, few authors suggest autolysis or fixation problems. Our WES resulted in newly found pathogenic mutations, and high mutation burden, proving the lesion's neoplastic origin. Hitherto, neither special stainings nor immunohistochemical markers proved to be useful in the diagnostic process. From a differential diagnostic perspective, enteroblastic differentiation, primary and secondary clear cell adenocarcinoma has to be excluded.

Mucinous Adenocarcinoma of the Colon with Clear Cell Component: A Case Report and Literature Review

Clear cell adenocarcinomas of the colon are defined as a subtype of colorectal adenocarcinoma with clear cell morphology. A 65-year old man was admitted to a Gastroenterology Department for diagnostic evaluation of a tumor in the sigmoid colon found on CT. There, the patient developed complete bowel obstruction and was operated urgently, where intraoperatively, a large tumor in the sigmoid fixated to the lateral abdominal wall was revealed. A subtotal colectomy was performed. Histopathological analysis of the surgical specimen was conducted. The immunohistochemistry staining was positive for CEA, CDX2, and CD20 and negative for CK7, CD10, MUC2, AFP, and PAS staining. Mismatch repair protein testing was negative. The pathological diagnosis was mucinous carcinoma with a clear cell component which bears an extremely low incidence that has been scarcely reported in literature. This stresses the need for more case reports like ours to be published.

Early stage clear cell adenocarcinoma coexisting with tubular adenoma and adenoma with clear cell change in the colon

Primary clear cell adenocarcinoma (CCA) of the colorectum is rare. We report a case of a 57-year-old man with early-stage CCA with conventional tubular adenoma and tubular adenoma with clear cell change in the transverse colon, diagnosed with image-enhanced endoscopy. The tumor was then treated with endoscopic submucosal dissection. The endoscopic findings characteristic of clear cell adenoma/adenocarcinoma could not be identified. Therefore, similar diagnostic tools as for conventional colorectal adenoma/cancer were considered. The pathogenesis of the clear cell change was unknown, but it might appear with the progression of the malignancy.

Incidental morphological findings in colorectal adenomas

Owing to a sharp increase in the frequency of diagnosis of colorectal adenomas in the current era of population screening, distinctive morphological features are increasingly being observed. These may present diagnostic challenges and cause clinical management issues. Paneth cell metaplasia is a more common occurrence, but the incidence rates of squamous metaplasia, clear cell metaplasia, osseous metaplasia, neuroendocrine differentiation and signet‐ring cell‐like lesion are low, and they can be seen in <1% of colorectal adenomas. Their histomorphological characteristics are quite unique; ancillary studies are not very helpful and often not needed. In this review, we give an overview and describe the potential clinical consequences of such incidental and special morphological findings in colorectal adenomas.

Colon adenoma and adenocarcinoma with clear cell components - two case reports

Background

Diagnoses reflect clear cell morphologies when tumor cells have clear cytoplasm in many organs, and the nature of such clear cells is typically identified. Colorectal tubular adenoma or adenocarcinoma, conversely, rarely show clear cells, the reason for which remains uncertain. We report 2 colon tumors with clear cell components (Case 1: adenoma; Case 2: adenocarcinoma) and investigate the nature of the clear cells.

Case presentation

Case 1 was a 75-year-old man with a superficial elevated polyp detected in the rectum for whom endoscopic submucosal dissection was performed. Microscopically, 10% of the tumor showed dysplastic columnar epithelium with clear cytoplasm forming tubular structures accompanied by conventional tubular adenoma. Case 2 was a 58-year-old man with a pedunculated polyp found in his sigmoid colon for which polypectomy was performed. Microscopically, 90% of the tumor showed dysplastic columnar epithelium with clear cytoplasm forming fused glands or cribriform structures adjacent to the ordinal tubular adenocarcinoma. In both cases, clear and ordinary tumor cells were negative for CK7 and positive for CK20 and CDX2, consistent with findings of colorectal origin. Different results were found for CEA and CD10 staining. CEA was positive on the luminal side of the conventional area in contrast diffuse cytoplasmic staining of the clear cell area in both cases. CD10 was only positive for the clear cell component of case 2. The clear cell components were negative for Periodic acid-Schiff (PAS), Alcian blue, and mucicarmine staining and AFP immunohistochemistry. An ultrastructural examination found multiple cytoplasmic lipid-like vacuoles in the clear cell component that were predominantly negative for adipophilin by immunoelectron microscopy.

Conclusions

We investigated tubular adenoma and tubular adenocarcinoma with clear cell components. The accompanying conventional tubular adenoma or adenocarcinoma cells helped us to evaluate the atypia of the clear cells. Diffuse cytoplasmic staining of CEA and CD10 suggested that the clear cell component might harbor malignant potential. We were unable to verify the well-known causes of clear cytoplasm, such as an accumulation of glycogen, lipid, or mucin and enteroblastic differentiation. The causes of clear cells in the colorectal region remain uncertain; however, possible explanations include autolysis and carbohydrate elution.

Early stage clear cell adenocarcinoma of the colon examined in detail with image-enhanced endoscopy: a case report

Primary clear cell adenocarcinoma (CCA) of the colorectum is a rare tumor. We report on a 48-year-old man with early stage CCA in the descending colon who underwent detailed examination with image-enhanced endoscopy, such as magnifying endoscopy with narrow-band imaging and crystal violet staining. The tumor was treated successfully with endoscopic mucosal resection at our hospital.

Clear cell colorectal carcinoma: Time to clarify diagnosis

Primary clear cell colorectal carcinoma (CCC) is a very rare entity accounting for only 35 cases reported in the Literature. CCC is neither classified as a distinct entity nor is it defined as a CRC variant because its ontogeny remains unclear. Most of the reported CCC were found in the distal colon in patients with a mean age of 56 years. Histologically, clear cell change is the main morphologic feature and may present in a "pure" form, composed exclusively of clear cells, or in a "composite" form, admixed with other morphologically different components. It is possible to distinguish two biologically different types of CCC, with different clinical-pathologic features, therapeutic management and diagnostic criteria: a) Intestinal CCC consisting of an aggressive neoplasm, affecting mainly adult men, characterized by an intestinal-type immunoprofile (CK20+, CK7-, CEA+, CDX-2+) and b) Müllerian CCC consisting of an indolent carcinoma of the sigmoid-rectum, affecting young women, characterized by a different (CK7+, CK20-, CEA-, CA125 +) immunoprofile. Considerable diagnostic difficulties can arise in distinguishing CCC and primary or secondary clear cell neoplasms, such as metastases from renal carcinoma, lower urinary tract, female genital tract, adrenal gland, mesothelioma, melanoma and primary intestinal PEComa. In this paper we review the Literature with two additional cases in order to define the diagnostic criteria of CCC.