Snowman-like appearance in spinal capillary hemangioma with combined intra- and extramedullary components: two case reports
This paper reports two rare cases of spinal capillary hemangioma with combined intra- and extramedullary components presenting a "snowman-like" MRI appearance, highlighting the importance of including this benign tumor in the differential diagnosis for such imaging patterns despite its typical association with hemangioblastoma.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Inside the human body, the spinal cord acts as a vital information highway, carrying messages between the brain and the rest of the body. This delicate bundle of nerves is protected by layers of tissue and fluid, but it is not immune to growths. Sometimes, benign tumors—non-cancerous lumps that do not spread to other parts of the body—can form within or around these protective layers. One such rare growth is the capillary hemangioma, a tumor made up of a dense tangle of tiny blood vessels. While these tumors are common in the skin and soft tissues of the head and neck, finding one inside the spinal cord is an unusual event. Because they are so rare and often look like other, more common spinal tumors on medical scans, doctors frequently struggle to identify them before surgery. Knowing exactly what a tumor is before cutting into the spine is crucial, as it helps surgeons plan the safest way to remove it and predict how a patient will recover.
Two researchers from Kanazawa University in Japan recently shared the stories of two patients who had this specific, rare condition. The first was a forty-six-year-old man who came in complaining of back pain and a loss of feeling in his mid-back. The second was a seventy-year-old woman who felt numbness in both of her legs. When doctors examined their spines using magnetic resonance imaging, a technique that uses magnetic fields to create detailed pictures of the inside of the body, they saw tumors that looked very similar in both patients. The growths were located in the middle of the back, and they appeared as bright, solid shapes on the scans. What made these cases particularly interesting was the shape of the tumors. Each one had two distinct parts: a section growing inside the spinal cord and another section growing just outside of it, separated only by a thin membrane called the pia mater. On the images, these two connected parts looked like a snowman, with a round top and a round bottom joined together.
This "snowman" shape had been seen before, but only in a different type of tumor called a hemangioblastoma. Because of this, doctors often assume that if they see this specific shape, the tumor must be a hemangioblastoma. However, the researchers in this study found that this assumption might be wrong. During surgery, both patients were found to have tumors that were extremely rich in blood vessels, appearing reddish and requiring careful management of the blood flow to remove them safely. The surgeons used a special dye and a camera to trace the blood vessels feeding the tumors, allowing them to remove the entire growth in one piece without damaging the surrounding nerves. When the removed tissue was examined under a microscope, the results were clear. The tumors were not hemangioblastomas; they were capillary hemangiomas. The cells showed a proliferation of tiny blood vessels without the specific features that would identify them as the other type of tumor.
The findings suggest that the snowman-like appearance is not a unique fingerprint for just one kind of tumor. Instead, it is simply the result of a growth that happens to start in the membrane surrounding the spinal cord and expand in both directions, pushing into the cord on one side and the space outside it on the other. This means that when a surgeon sees a spinal tumor with this dual-part shape, they should not automatically rule out capillary hemangioma. In both cases described, the patients recovered well after the surgery. The spinal cord swelling seen on the scans went down, and the patients' symptoms improved significantly, with the man's back pain disappearing and the woman's leg numbness nearly resolving. The study serves as a reminder that even rare tumors can have familiar shapes, and that looking closely at the specific details of a growth is necessary to make the correct diagnosis and provide the best care.
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