P2331 - A Rare Case of Primary Clear Cell Adenocarcinoma of the Colon

Gowthami Ramar, MD¹, Minhaz Ahmad, MD¹, Atif Saleem, MD¹, Ali Timsar, MD^2
1United Health Services, Johnson City, NY; ²UHS Wilson Hospital, Johnson City, NY

Introduction: Primary clear cell adenocarcinoma of the colon is a rare neoplasm. Despite advancements in the techniques of pathological examination and immune-histochemistry over the past years, this tumor has only been rarely diagnosed in the colon. We report a rare case of a primary clear cell adenocarcinoma of the caecum in an elderly female.

Case Description/Methods: A 76 year old female presented with complaints of abdominal pain, vomiting and diarrhea for 5 days without hematochezia or melena. Exam revealed tenderness on palpation in the right lower quadrant. Lab was significant for normocytic anemia. CT Abdomen revealed 63.9mm neoplastic mass in the cecum with almost complete occlusion of distal and terminal ileum with adjacent lymphadenopathy and evolving small bowel obstruction. Patient was taken to the operating room where she was found to have large mass in the cecum invading retroperitoneal space. Cecum was mobilized, resected and anastomosed. Gross exam revealed 9.3*5.5cm circumferential tumor mass involving the area of cecum, distal terminal ileum and portions of proximal ascending colon. Histopathology revealed neoplasm with sheets of infiltrative malignant cells with marked atypia, pleomorphism, prominent nucleoli and high mitotic activity diffusely involving the colonic wall with extensive necrosis. Tumor cells have abundant clear cytoplasm indicating clear cell carcinoma .2/54 lymph nodes were positive for metastatic neoplasm. No lympho-vascular or perineural invasion was noted. Patient was discharged home with a plan for outpatient chemotherapy.

Discussion: Most clear cell adenocarcinomas of the colon are metastasized from other organs including kidney, lower urinary tract, ovaries and female genital tract. It is important to differentiate primary from metastatic clear cell carcinoma of the colon. Lack of hypervascularity in the tumor, lack of immunoreactivity for PAX2, PAX8, RCC, Vimentin, no diffuse membranous and box like CAIX expression rule against a diagnosis of clear renal cell carcinoma. There was no evidence of tumor elsewhere on imaging in this patient. All reported cases of primary clear cell carcinomas of the colon in literature were found in males and on the left side of the colon. However, our patient is an elderly female with tumor on the right side of the colon. Clinical data regarding tumor mortality and disease free survival in patients with primary clear cell adenocarcinoma of the colorectal region is rare, because of the rarity of the condition.


Figure: A -CT Abdomen showing 63.9mm neoplastic mass in the cecum
B -Nuclear atypia and pleomorphism, abundant clear cytoplasm, increased mitosis and abnormal mitotic figures
C -SAT B2 positivity -as seen in neoplasms of colorectal origin
D -AE1:AE3 diffusely positive in neoplastic cells confirming epithelial origin of tumor


Disclosures:
Gowthami Ramar indicated no relevant financial relationships.
Minhaz Ahmad indicated no relevant financial relationships.
Atif Saleem indicated no relevant financial relationships.
Ali Timsar indicated no relevant financial relationships.


Gowthami Ramar, MD¹, Minhaz Ahmad, MD¹, Atif Saleem, MD¹, Ali Timsar, MD². P2331 - A Rare Case of Primary Clear Cell Adenocarcinoma of the Colon, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.