MUCINOUS AND SIGNET RING CELL RECTAL ADENOCARCINOMA WITH ISOLATED BONE MARROW DISSEMINATION: A CASE REPORT

Case Presentation A 56-year-old male, hypertensive, was admitted to the emergency department of a tertiary hospital on 03/20/2023 with a one-month history of lower back pain radiating to the lower limbs, associated with asthenia, anorexia, hematochezia, and a 4 kg weight loss, without prior colonoscopy. On admission, moderate bicitopenia and elevated LDH were observed. A computed tomography (CT) scan revealed concentric thickening of the rectal wall with adjacent mesorectal fat densification and locoregional lymph nodes, suggesting primary rectal neoplasia. On proctological examination, a fixed lesion with irregular mucosa was found on the anterolateral left wall of the rectum, 6 cm from the anal margin. A colonoscopy was scheduled for 04/05/2024 but was postponed due to clinical worsening and refractory bicitopenia. On 04/05/2023, a bone marrow biopsy showed extensive infiltration by mucinous adenocarcinoma with signet-ring cells, low hematopoietic reserve, and grade 3 reticulin fibrosis. Immunohistochemistry confirmed a colorectal primary site. After a multidisciplinary discussion, a palliative approach was chosen due to the refractory bicitopenia to transfusion measures (9 units of red blood cells and 27 units of platelets during the entire hospitalization), as well as the mucinous subtype's poor response to chemotherapy. The patient was discharged after 23 days of hospitalization for outpatient follow-up but discontinued follow-up care.

Discussion Rectal cancer with isolated bone marrow dissemination is extremely rare, occurring in 0–1.1% of patients. This type of dissemination can lead to hematologic dysfunction, with the most common symptoms being anemia, lower back pain, and a tendency to bleed, though this initial presentation without changes in bowel habits is uncommon. The main predictive factors for bone marrow metastasis include the rectal origin of the tumor, signet-ring cell characteristics, receipt of systemic chemotherapy, presence of pulmonary metastases, and higher tumor grade in patients with multiple metastatic sites. However, the association with isolated bone marrow metastasis has not been established. The prognosis is poor, regardless of treatment, with a survival rate of 3 months in many cases.

Conclusion This case highlights the importance of investigating bicitopenia, with colorectal cancer being a diagnostic consideration even in the absence of gastrointestinal symptoms.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
25 April 2025