Myopericytoma: A Rare Benign Tumor of the Foot and Ankle
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Benign tumors are collections of abnormal cells that grow with smooth, well-defined borders and do not spread to other areas of the body. They can still cause complications, however, depending on their size or location. There are many different types of benign tumors, each named according to the specific tissue they develop from.1
Pericytes are cells located along the walls of capillaries which have several important functions, the most significant being the regulation of blood flow. They achieve this through extensions that wrap around the capillary, allowing them to control and support proper circulation.2 A myopericyte is a cell that shares features of both myoid, or muscle, cells and pericytes.3 When a benign tumor develops from myopericytes, it is called a myopericytoma. These tumors are very rare and can sometimes be mistaken for sarcomas.3 Most commonly seen in younger adults, they most often arise in the dermis and/or subcutaneous tissue. Myopericytomas are usually slow-growing and painless, frequently occurring as a single growth, though multiple tumors can develop. Recurrence is uncommon but has been reported in some cases, and this tumor is capable of undergoing malignant transformation.4 According to one source, myopericytomas are most commonly found in the lower extremities and may become malignant in up to 20% of people.5
A Closer Look at a Case Example
A 40-year-old male of South Asian descent presented to the podiatry office with an enlarging mass in his right ankle, specifically in the subfibular region. The patient reported first noticing the mass approximately 2 years ago. On the initial exam, the patient had palpable pedal pulses and intact neurological status. There were no skin changes noted around the mass. Since then, it had gradually enlarged and began to interfere with his work as a cab driver, specifically with pain when wearing shoes. He described the pain as a mild, dull, throbbing sensation, worsened by movement.
A plain film X-ray of the right foot revealed no significant findings. Subsequent magnetic resonance imaging (MRI) with and without contrast showed a 4.0 x 3.0 x 2.4 cm heterogenous enhancing mass. The MRI interpretation also noted multiple nonenhancing internal components to the mass, a few of which demonstrated an intrinsic hyperintense signal on T1-weighted images. The remainder of the mass did exhibit enhancement on post-contrast images. The impression stated that the most likely diagnoses included sarcoma or peripheral nerve sheath tumor (of the sural nerve). A less possible, and less favored differential diagnosis was a vascular lesion.
Details of the Treatment Course
After counseling the patient on potential diagnoses and management options, he elected to proceed with surgical excision. Upon dissection for the excision, one could see that the mass contained multiple blood vessels. These vessels were ligated and cauterized, and several small nerve branches were sacrificed due to their involvement within the mass. Visualization of the peroneal tendons took place during the procedure, and there did not appear to be any continuity or involvement with the mass. Following complete removal, no conspicuous abnormal tissue remained. The excised mass was sent to pathology for further evaluation. The patient did initially suffer a small central dehiscence of his incision, but by 1 month post-surgery he had fully healed, and after 3 months there has been no evidence of recurrence.
Pathology received the excised mass, measuring 4.0 x 3.0 x 2.0 cm. They described the specimen as capsular and red, covered by thin fibrous adhesions and adipose tissue. Microscopic examination revealed numerous thick-walled blood vessels arranged concentrically, with ovoid-to-spindled tumor cells containing abundant cytoplasm. Areas of dilated, thrombosed vessels, scarring, old hemorrhage, and degenerative changes were also noted. Immunohistochemical analysis showed SMA (smooth muscle actin) positivity, indicating smooth muscle features,6 Ki-67 <1%, usually found with a benign lesion,7 and CD34 positivity in the endothelial lining, confirming the presence of blood vessels.6 All other immunostains were negative, and the pathologist supported a diagnosis of a myopericytoma.
In Conclusion
This case emphasizes the importance of considering myopericytoma in the differential diagnosis of foot and ankle masses. While rare and typically benign, these tumors can often mimic other soft tissue lesions and cause functional impairment when they enlarge or involve nearby structures. For podiatrists, careful clinical evaluation combined with imaging, surgical excision, and confirmatory pathology is key to effective management. Complete removal is usually curative, and recurrence is uncommon in which only about 10–20% of patients do have recurrence occur,8 making timely diagnosis and intervention essential to improve patient outcomes.
Dr. Kaplan is a Diplomate of the American Board of Foot and Ankle Surgery and is certified in Foot Surgery. He is a partner in Family Footcare Group, LLP, in New York. He is also consulting staff at Garnet Health Medical Center Catskills, attending staff at Garnet Health Medical Center Middletown, surgeon at Hudson Valley Ambulatory Surgery Center, and attending staff at Garnet Wound Care Center Middletown.
Jacob Kaplan has received a Bachelors of Science in Ecology and Evolutionary Biology at Tulane University.
References
1. Cleveland Clinic. Are benign tumors cancer? Published June 2, 2025. Accessed October 9, 2025. https://my.clevelandclinic.org/health/diseases/22121-benign-tumor
2. McKenzie S. Pericytes: Purpose and function. News-Medical Life Sciences. Published February 26, 2019. Accessed October 9, 2025. https://www.news-medical.net/life-sciences/
Pericytes-Purpose-and-Function.aspx
3. Dray MS, McCarthy SW, Palmer AA, et al. Myopericytoma: A unifying term for a spectrum of tumours that show overlapping features with myofibroma. A review of 14 cases. J Clin Pathol. 2006;59(1):67-73. Accessed October 9, 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC1860256/
4. Manner J, Bonetti F, Requena L, et al. Update on vascular neoplasms. Dermatol Clin. 2012;30(4):633-649. Published August 15, 2012. Accessed October 9, 2025. https://www.sciencedirect.com/science/article/abs/pii/S0733863512000836
5. Manole S, Pintican R, Manole V, et al. Rare case of intravascular myopericytoma—Imaging characteristics and review of the literature. Diagnostics. 2022; 12(10):2473. https://doi.org/10.3390/diagnostics12102473
6. Miettinen M. Immunohistochemistry of soft tissue tumours—review with emphasis on 10 markers. Histopathology. 2014;64(1):101-118. Accessed October 9, 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC7670586/
7. National Cancer Institute. NCI dictionary of cancer terms: Ki-67 score. Accessed October 9, 2025. https://www.cancer.gov/publications/dictionaries/cancer-terms/def/ki-67-score.
8. Science Direct. Myopericytoma. Available at: https://www.sciencedirect.com/topics/medicine-and-dentistry/myopericytoma. Published 2025. Accessed October 14, 2025.
