Abstract: Unexplained Microcytosis in a 40-Year-Old Male: Case Report of a Missed Opportunity for Early Colorectal Cancer Diagnosis.
In the United States, colorectal cancer ranks as the third most commonly diagnosed malignancy and the second leading cause of cancer-related death in both men and women. Colorectal cancer incidence is rising among people under the age of 50 who account for an estimated 13% of cases. Colon cancer typically develops slowly over the course of five to ten years, so primary care physicians should maintain a high index of suspicion for early clinical indicators of potential malignancy to promote timely detection.
We report the case of a 40-year-old male with a history of morbid obesity (BMI 54 kg/m2), type 2 diabetes mellitus, and hypertension with isolated microcytosis (MCV 77.1 fL, hemoglobin 13.9 g/dL) and iron deficiency (iron 35 ug/dL, ferritin 68 ng/mL) during an annual wellness visit. The patient re-established care five years later and reported intermittent rectal bleeding that he owed to hemorrhoids. Labs were notable for iron deficiency anemia (hemoglobin 11.7 g/dL, MCV 69.2 fL, iron 17 ug/dL, ferritin 26 ng/mL). Colonoscopy revealed a partially obstructing infiltrating and circumferential tumor in the descending colon and several large, scattered pedunculated polyps. Biopsies confirmed invasive adenocarcinoma with intact expression of mismatch repair genes. Staging CT scan was unable to localize a colonic mass but identified clustered enlarged metastatic lymph nodes. Stage IIIb colon adenocarcinoma (cT3 cN1b cM0) was treated with neoadjuvant chemotherapy (mFOLFOX 6) followed by a left hemicolectomy eight months after the diagnosis with remission.
Iron deficiency anemia is a well-known clinical indicator for colorectal cancer. Any early signs of anemia including isolated microcytosis in men or post-menopausal women should be further investigated for gastrointestinal blood loss. With rising incidence of colorectal cancer in younger adults, laboratory abnormalities warrant thorough evaluation as they may be the only indicator of occult blood loss from malignancy.
We report the case of a 40-year-old male with a history of morbid obesity (BMI 54 kg/m2), type 2 diabetes mellitus, and hypertension with isolated microcytosis (MCV 77.1 fL, hemoglobin 13.9 g/dL) and iron deficiency (iron 35 ug/dL, ferritin 68 ng/mL) during an annual wellness visit. The patient re-established care five years later and reported intermittent rectal bleeding that he owed to hemorrhoids. Labs were notable for iron deficiency anemia (hemoglobin 11.7 g/dL, MCV 69.2 fL, iron 17 ug/dL, ferritin 26 ng/mL). Colonoscopy revealed a partially obstructing infiltrating and circumferential tumor in the descending colon and several large, scattered pedunculated polyps. Biopsies confirmed invasive adenocarcinoma with intact expression of mismatch repair genes. Staging CT scan was unable to localize a colonic mass but identified clustered enlarged metastatic lymph nodes. Stage IIIb colon adenocarcinoma (cT3 cN1b cM0) was treated with neoadjuvant chemotherapy (mFOLFOX 6) followed by a left hemicolectomy eight months after the diagnosis with remission.
Iron deficiency anemia is a well-known clinical indicator for colorectal cancer. Any early signs of anemia including isolated microcytosis in men or post-menopausal women should be further investigated for gastrointestinal blood loss. With rising incidence of colorectal cancer in younger adults, laboratory abnormalities warrant thorough evaluation as they may be the only indicator of occult blood loss from malignancy.