Multiple Strokes Lead to Hidden Colorectal Cancer Diagnosis in Rare Case

“This case highlights the importance of early consideration of occult malignancy in cryptogenic embolic events, supporting comprehensive oncologic evaluation for unexplained hypercoagulable states.”

BUFFALO, NY — September 24, 2025 — A new case report was published in Volume 12 of Oncoscience on September 15, 2025, titled “When strokes reveal a hidden malignancy: An atypical case of metastatic colorectal cancer with extensive thromboembolism.”

In this case report, Md Tanzim Ahsan from Wrightington, Wigan and Leigh (WWL) Teaching Hospitals, NHS Foundation Trust and Sultana Azreen from Clatterbridge Cancer Centre, describe how a series of unexplained strokes led to the diagnosis of advanced colorectal cancer. The report shows that hidden cancers can sometimes first present through blood clots and strokes, well before any typical cancer symptoms appear. These findings highlight the importance of evaluating cancer as a possible cause of unexplained embolic events, particularly in the absence of traditional stroke risk factors. 

“Although symptoms raised initial suspicion for vasculitis or autoimmune etiologies due to limb swelling and headache, he did not report associated visual disturbances, nausea, vomiting, or neurological deficits.”

The patient, a 71-year-old man, was admitted to the hospital with swelling in his left arm, headache, and non-specific neurological symptoms. Over the following weeks, he suffered multiple strokes affecting different areas of the brain, as well as blood clots in his veins, lungs, kidneys, and spleen. Clinicians initially suspected autoimmune conditions or infection. However, imaging and blood exams revealed signs of cancer. A biopsy of an enlarged lymph node confirmed metastatic colorectal cancer that had silently spread throughout the body.

The patient had no typical symptoms of colorectal cancer, such as weight loss, digestive issues, or changes in appetite. Because of this, the cancer remained undetected until widespread blood clot complications appeared. By the time the diagnosis was confirmed, the care team transitioned the patient to palliative care, as the disease was too advanced for curative treatment.

This case illustrates a serious but often underrecognized condition known as Trousseau’s syndrome, or cancer-associated stroke. It occurs when cancer causes abnormal blood clotting, leading to clots throughout the body. Unlike strokes caused by heart conditions, cancer-related strokes often involve multiple brain regions and lack clear cardiac causes. Elevated blood clotting markers, such as D-dimer, can serve as potential indicators of hidden malignancy in such patients.

The findings underscore the growing awareness that cancer may present in subtle, non-specific ways, sometimes through neurological or vascular symptoms. Clinicians are encouraged to maintain a high level of suspicion when evaluating patients with unexplained strokes, especially when imaging reveals multiple infarcts or embolic patterns without an identifiable source.

The authors call for the development of clearer clinical guidelines to help healthcare providers recognize and screen for underlying cancers in stroke patients without obvious risk factors. As cancer rates continue to rise worldwide, early recognition of indirect warning signs, such as abnormal clotting, may allow earlier detection and improve patient outcomes.

DOI: https://doi.org/10.18632/oncoscience.626

Correspondence to: Md Tanzim Ahsan – md.ahsan@wwl.nhs.uk

Keywords: cancer, trousseau’s syndrome, cancer-associated stroke (CAS), hypercoagulability, colorectal cancer, systemic thromboembolism

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