Primary Solitary Fibrous Tumor of the Lacrimal Sac Mimicking Lymphoma: A Case Report
This case report describes a rare primary solitary fibrous tumor of the lacrimal sac in a 50-year-old man that clinically mimicked chronic dacryocystitis and radiologically suggested lymphoma, ultimately diagnosed via STAT6 immunohistochemistry and successfully treated with complete surgical excision and bicanalicular intubation.
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
In the quiet corner of the face where the eye meets the nose, a small system of tubes works tirelessly to drain tears. When these tubes become blocked, the area can swell, become red, and feel tender, mimicking a common infection known as chronic dacryocystitis. For decades, doctors have treated this swelling with antibiotics and warm compresses, assuming the worst was a simple bacterial issue. However, the human body is capable of growing unusual masses of tissue that do not behave like infections. One such growth is a solitary fibrous tumor, a rare type of soft tissue mass that can appear almost anywhere in the body but is exceptionally uncommon in the tear drainage system. Because these tumors grow slowly and painlessly, they often hide in plain sight, looking exactly like a harmless infection until they are large enough to cause concern. Distinguishing between a stubborn infection, a cancer of the blood cells called lymphoma, and a solitary fibrous tumor is difficult because they can look identical to the naked eye and even to the cameras used in medical imaging. Getting the diagnosis right matters deeply, as the treatment for an infection is medication, while the treatment for a tumor is surgery, and confusing the two can delay the cure.
A team of doctors at the Beijing Hospital of Integrated Traditional Chinese and Western Medicine recently shared the story of a fifty-year-old man who fell into this diagnostic trap. For two years, he lived with a painless, slowly growing lump at the inner corner of his right eye. When he first sought help, a different hospital diagnosed him with the common tear duct infection and prescribed eye drops and warm compresses. For three months, the treatment failed; the swelling did not shrink. When the man returned for further evaluation, a magnetic resonance imaging scan, which uses powerful magnets to create detailed pictures of the inside of the body, showed a mass that looked suspicious. The radiologist who read the scan suspected lymphoma, a type of cancer that affects the immune system, because the image did not show the typical features of the rare fibrous tumor. The doctors decided to remove the mass entirely to find out what it was, using a small cut near the inner corner of the eye to access the tear sac.
Inside the operating room, the surgeons found a firm, rubbery, grayish-white mass measuring about two centimeters, which is roughly the size of a large grape. They removed the entire tumor along with a small margin of healthy tissue to ensure nothing was left behind. Because the tumor had taken the place of the tear duct, the surgeons also placed a thin silicone tube through the drainage system to keep it open while it healed. The surgery was successful, with very little blood loss, and the patient recovered quickly. However, the true answer to the mystery lay not in the operating room, but under a microscope in the pathology lab. When the tissue was sliced thin and stained, the cells revealed a pattern of long, spindle-shaped shapes arranged in a chaotic but distinct way. To be certain, the doctors used a special chemical test that looks for a specific protein called STAT6. This protein acts like a unique fingerprint for solitary fibrous tumors. The test showed a strong, clear signal for this protein, confirming that the mass was indeed a solitary fibrous tumor and not the lymphoma the scan had suggested.
The result was a clear diagnosis that explained the man's two-year struggle. The tumor was growing slowly and was not aggressive, as indicated by a very low rate of cell division found in the sample. The doctors removed the tumor completely and repaired the tear drainage system in a single procedure. One month after the surgery, the patient's eye was draining tears normally, the incision had healed, and there was no sign that the tumor had returned. This case highlights a critical lesson for medical practice: when a lump near the eye does not respond to standard infection treatments, waiting longer is not the answer. The doctors learned that relying on imaging alone can be misleading, as this rare tumor can look like lymphoma on a scan. Instead, removing the mass and testing it for the specific protein marker provides a definitive answer. By identifying the tumor correctly and removing it early, the patient avoided unnecessary delays and received the precise care he needed to restore both his vision and his comfort.
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