An Incidental Finding of Anemia: Rectal Adenocarcinoma in a Young Adult

Rectal adenocarcinoma is an uncommon finding in patients under the age of 40. However, epidemiological surveys have suggested that colorectal cancers are increasing in incidence among patients aged 20 to 39 years in the United States. Colorectal adenocarcinoma is often not considered in the differential diagnosis in this demographic because of age. Here, we present the case of an incidental finding of anemia during a preliminary evaluation of rheumatoid arthritis leading to the diagnosis of stage IV-B rectal adenocarcinoma in a 34-year-old male patient. A 34-year-old Caucasian male presented with the incidental finding of anemia during a preliminary evaluation for rheumatoid arthritis. The patient was asymptomatic with the exception of a three-month history of wrist and ankle joint pain. Past medical history was positive for only a three-year history of occasional spotty, painless rectal bleeding attributed to internal hemorrhoids. Physical exam findings were positive for mild extremity pallor and positive fecal occult blood test. Hematologic studies revealed a significant microcytic, hypochromic anemia with severe iron deficiency. Laboratory studies revealed no evidence of vitamin deficiency, hemolytic activity, hematuria, hypothyroidism, or clotting factor disorder. Erythrocyte sedimentation rate (ESR), rheumatoid factor, and cyclic citrullinated peptide 3 (CCP3) were elevated supporting the diagnosis of underlying rheumatoid arthritis. On further questioning, the patient revealed that he had been utilizing an average of 2000 mg of ibuprofen daily during the previous several months in an attempt to control his joint pain. The patient was evaluated for a potential upper gastrointestinal bleed by esophagogastroduodenoscopy (EGD), which found no evidence of active bleeding. As the patient continued to have decreasing hemoglobin levels, he was evaluated for a lower gastrointestinal source of bleeding by colonoscopy, which revealed an 8 cm circumferential mass at the anal verge. Pathological evaluation of biopsy samples revealed a moderately differentiated invasive adenocarcinoma. The patient had no family history of colorectal cancer or major associated risk factors, such as obesity, smoking history, heavy alcohol use, diabetes mellitus type 2, or a history of inflammatory bowel disease. Following discharge, positron emission tomography (PET) scan showed extensive metastatic disease to multiple regional lymph nodes as well as multiple suspicious hepatic lesions and bilateral pulmonary nodules. Due to the poor prognosis, recommended treatment consisted of folinic acid, 5-fluorouracil, oxaliplatin (FOLFOX-4) along with palliative radiation. The cause of the increase in the incidence rate of colorectal cancer in young adults remains unknown. Among this demographic, colorectal cancers appear to be more aggressive and present at later stages with more advanced disease. In young adults, the most common clinical sign at presentation is rectal bleeding. In young adults presenting with seemingly common gastrointestinal complaints, a high degree of suspicion for colorectal cancer may be warranted by clinicians.