Spindle cell hemangioma is a benign vascular tumor that typically appears in the skin or just beneath it, most often in the hands, feet, and other parts of the extremities. Once thought to be a low-grade cancer, it has been reclassified over the past few decades as a benign lesion, though its tendency to recur locally and sometimes appear in clusters can make it a source of real frustration and pain for people who have it. The underlying genetics, particularly mutations shared with certain bone tumors, have reshaped how researchers understand this growth and its place among vascular anomalies.
What a Spindle Cell Hemangioma Actually Is
The name describes what pathologists see under the microscope: a mix of dilated, blood-filled vascular spaces (the “hemangioma” part) alongside areas packed with elongated, spindle-shaped cells. Those two components give the tumor its distinctive look and also explain why it was historically misidentified. When it was first described in 1986, it was called “spindle cell hemangioendothelioma” and classified as a vascular tumor with low malignant potential, partly because the spindle cell zones resembled Kaposi sarcoma and the cavernous vascular spaces looked like a standard hemangioma mashed together.
1PubMed. Spindle cell hemangioendothelioma. A low-grade angiosarcoma resembling a cavernous hemangioma and Kaposi’s sarcomaA landmark reanalysis of 78 cases later concluded that spindle cell hemangioma behaves as a primary benign vascular neoplasm or malformation, where changes in blood flow within the lesion explain its microscopic features. Areas of sluggish flow lead to vascular collapse, forming those dense “cellular” zones of spindle cells, while areas of engorgement promote clotting and organization within the vascular spaces.
2PubMed. Spindle cell hemangioendothelioma. An analysis of 78 cases with reassessment of its pathogenesis and biologic behaviorThat shift in understanding, from “low-grade angiosarcoma” to “benign lesion,” is the single most important thing about spindle cell hemangioma for patients. It means the growth does not spread to distant organs. Local recurrence and multicentric growth (new nodules popping up in the same region) are common, but metastasis does not happen in the typical case.
Where It Shows Up and Who Gets It
Spindle cell hemangiomas appear as red-brown or blue-red nodules in the dermis or subcutaneous tissue, and they have a strong preference for the extremities. In a clinicopathologic study of 18 cases, about two-thirds of tumors occurred in the hands and feet, and 94% occurred somewhere in an extremity. The age range was broad, from 12 to 78 years, with a median around 38 or 39.
3The American Journal of Surgical Pathology. Epithelioid and Spindle Cell Hemangioma: Clinicopathologic Analysis of 18 Primary Bone and Soft Tissue Tumors Highlighting a Predilection for the Hands and Feet, Frequent Multicentricity, and Benign BehaviorA striking feature is how often the tumors are multiple. In that same series, half of patients had more than one tumor, and the multifocal tumors were always clustered in a single anatomic region on one side of the body, such as a hand and wrist or an ankle and foot. This unilateral, regional clustering is a hallmark and can help a clinician suspect the diagnosis before the biopsy results come back.
4The American Journal of Surgical Pathology. Epithelioid and Spindle Cell Hemangioma: Clinicopathologic Analysis of 18 Primary Bone and Soft Tissue Tumors Highlighting a Predilection for the Hands and Feet, Frequent Multicentricity, and Benign BehaviorAlthough the distal extremities are the classic location, spindle cell hemangiomas can occasionally appear in less expected places. Cases have been documented in the oral cavity, including the sublingual region and the upper lip, as well as in bone and even the spleen. These atypical sites are rare enough to prompt individual case reports, which underscores how unusual they are.
5PubMed Central. Spindle Cell Hemangioma in the Mucosa of the Upper Lip: A Case Report and Review of the LiteratureSymptoms and Daily Impact
Spindle cell hemangiomas are not just cosmetic. They can be very painful and potentially disabling, especially when they involve the hands or feet.
6PubMed Central. Spindle Cell Hemangioma and Atypically Localized Juxtaglomerular Cell Tumor in a Patient with Hereditary BRIP1 Mutation: A Case Report A case report of a 35-year-old woman with a spindle cell hemangioma in the midfoot illustrates the pattern well: she experienced pain when walking or standing, the symptoms worsened with exercise, and she had been dealing with recurrent pain for five years before treatment. Medication alone did not help, and the symptoms progressively worsened.
7PubMed Central. Spindle Cell Hemangioma of the Midfoot: A Case ReportBecause the tumors tend to grow in number over time and can recur after removal, people with spindle cell hemangioma sometimes go through cycles of surgery, regrowth, and more surgery. When the lesions are in the fingers or palm, this can directly interfere with grip strength and fine motor function. The emotional and functional burden is real, even though the tumors themselves are not cancerous.
The IDH Mutation Connection
The molecular story of spindle cell hemangioma is one of the more interesting findings in vascular tumor genetics. Roughly seven in ten spindle cell hemangiomas carry a mutation in either the IDH1 or IDH2 gene. In a study of 28 cases, about 64% had a specific IDH1 mutation (R132C), and two additional cases carried IDH2 mutations, bringing the total to 71%.
8PubMed. R132C IDH1 mutations are found in spindle cell hemangiomas and not in other vascular tumors or malformationsWhat makes this especially notable is the specificity. That same study tested 154 other vascular tumors and malformations for the same IDH1 mutation and found it in none of them. IDH mutations are well known in other contexts, particularly in certain brain tumors and blood cancers, but in the world of vascular lesions, they appear to be a signature of spindle cell hemangioma.
9PubMed. R132C IDH1 mutations are found in spindle cell hemangiomas and not in other vascular tumors or malformationsIDH enzymes play a role in cellular metabolism, and when they are mutated, they produce an abnormal metabolite that can alter how cells grow and differentiate. In spindle cell hemangioma, these mutations appear to be somatic, meaning they arise in individual cells during a person’s lifetime rather than being inherited from a parent. This fits with the observation that the tumors tend to be clustered in one region of the body rather than scattered everywhere.
Maffucci Syndrome and Ollier Disease
Spindle cell hemangiomas are one of the defining features of Maffucci syndrome, a rare condition in which multiple benign cartilage tumors called enchondromas develop alongside vascular lesions. The IDH mutations that characterize spindle cell hemangiomas also drive the enchondromas in these syndromes. Research on patients with Ollier disease and Maffucci syndrome found IDH1 or IDH2 mutations in 87% of enchondromas and 70% of spindle cell hemangiomas, suggesting a shared molecular origin.
10PubMed Central. Somatic mosaic IDH1 and IDH2 mutations are associated with enchondroma and spindle cell hemangioma in Ollier disease and Maffucci syndromeIn Maffucci syndrome, the spindle cell hemangiomas and enchondromas are thought to arise from somatic mosaic mutations, meaning the mutation occurs early in embryonic development and affects only a subset of the body’s cells. That mosaic distribution explains why the tumors cluster in certain anatomic regions rather than appearing everywhere. A study of six patients with Maffucci syndrome confirmed that all of their vascular lesions were spindle cell hemangiomas, and none had metastasized over an average follow-up of 20 years.
11PubMed. Multiple enchondromas associated with spindle-cell hemangioendotheliomas. An overlooked variant of Maffucci’s syndromeThe concern with Maffucci syndrome lies not in the spindle cell hemangiomas themselves but in the enchondromas, which carry a risk of malignant transformation to chondrosarcoma. In one reported case, a patient died from metastatic dedifferentiated chondrosarcoma, and another had a splenic vascular tumor with features of low-grade angiosarcoma alongside spindle cell hemangioma-like areas. These rare but serious complications mean that patients with Maffucci syndrome need ongoing monitoring, even though the spindle cell hemangiomas themselves are benign.
12PubMed. Multiple enchondromas associated with spindle-cell hemangioendotheliomas. An overlooked variant of Maffucci’s syndromeHow It Is Diagnosed
Diagnosis usually requires a biopsy with microscopic examination. On imaging, spindle cell hemangiomas in bone show up as osteolytic lesions with a characteristic “soap bubble” appearance on X-ray and CT. On MRI, they typically appear as lobulated masses with low signal on T1-weighted sequences, heterogeneous high signal on T2, and enhancement after contrast administration. The lesions can occasionally look aggressive on imaging, with bone destruction and a soft tissue component, which can initially raise concern for something more serious.
13PubMed Central. Rare spindle cell hemangioma of bone: Case report and literature reviewUnder the microscope, pathologists look for the dual pattern of cavernous vascular spaces and spindle cell zones. Immunohistochemical staining helps confirm that the cells lining the vascular spaces are endothelial in origin. Markers commonly used include CD31, CD34, factor VIII, and Wilms tumor-1, all of which stain positively in the endothelial cells lining the cavernous spaces. The spindle cells in the solid areas show a more mixed staining pattern, reacting variably for most markers except factor VIII.
14PubMed Central. Spindle Cell Hemangioma in the Mucosa of the Upper Lip: A Case Report and Review of the LiteratureThe presence of occasional epithelioid endothelial cells with intracytoplasmic vacuoles (small fluid-filled pockets within cells, thought to represent primitive vessel formation) is another diagnostic clue and helps distinguish spindle cell hemangioma from its main mimics.
Telling It Apart from More Dangerous Tumors
The resemblance to Kaposi sarcoma is probably the most clinically consequential lookalike, because Kaposi sarcoma is a true malignancy. Several features help pathologists distinguish the two. Kaposi sarcoma tends to be more infiltrative, shows higher rates of cell division, and has more pronounced nuclear irregularity. Crucially, Kaposi sarcoma stains positive for HHV-8 (the virus that causes it), while spindle cell hemangioma does not.
15PubMed Central. Immunohistochemical Analysis of Oral Spindle Cell Hemangioma Additionally, the spindle cells in Kaposi sarcoma are usually positive for CD34, whereas in spindle cell hemangioma the spindle cells themselves tend to be negative or only variably positive for that marker.
16PubMed Central. Immunohistochemical Analysis of Oral Spindle Cell HemangiomaClinically, Kaposi sarcoma in bone almost always occurs in advanced HIV infection and involves multiple organ systems simultaneously, which is a very different presentation from a single cluster of nodules on someone’s hand or foot.
17Cancer. Hemorrhagic epithelioid and spindle cell hemangioma: A newly recognized, unique vascular tumor of boneOther tumors in the differential diagnosis include epithelioid hemangioendothelioma and epithelioid angiosarcoma. Epithelioid hemangioendothelioma has cells arranged in a distinctive corded pattern within a hyalinized or cartilage-like stroma, neither of which is seen in spindle cell hemangioma. Epithelioid angiosarcoma, a more aggressive malignancy, lacks the lobular growth pattern of spindle cell hemangioma and shows far greater nuclear irregularity and abnormal mitotic figures.
18Cancer. Hemorrhagic epithelioid and spindle cell hemangioma: A newly recognized, unique vascular tumor of boneTreatment and the Recurrence Problem
The standard treatment is surgical excision. Because the tumors are benign, wide margins are not necessary, and conservative removal is generally preferred. The challenge is recurrence. Spindle cell hemangiomas have a well-documented tendency to come back after surgery, and in patients with multiple tumors, new lesions may continue to develop in the same region over time. This does not mean the surgery failed in the traditional sense; it reflects the underlying biology of the condition, particularly in patients whose tumors are driven by mosaic IDH mutations affecting a population of cells in that region.
For patients with Maffucci syndrome, in whom spindle cell hemangiomas can be numerous, painful, and mutilating, repeated surgeries are sometimes an inadequate long-term solution. A case report described a 12-year-old boy with Maffucci syndrome whose spindle cell hemangiomas recurred rapidly after repeated surgical removal, causing significant dysfunction in his hand. The lesions were described as progressive and mutilating, with swelling of the palm and fingers and partially compressible vascular nodules clustered over one hand.
19Clinical and Experimental Dermatology. Successful sirolimus treatment of spindle cell haemangiomas in a paediatric patient with Maffucci syndromeIn that case, sirolimus (also known as rapamycin), a drug that suppresses cell proliferation through the mTOR pathway, was tried and reportedly achieved a successful treatment response. Sirolimus has gained traction as a medical option for various vascular anomalies that are difficult to manage surgically, and its use in spindle cell hemangioma is part of that broader trend. It is not yet a standard therapy, and published evidence is limited to individual case reports, but for patients who face repeated surgeries with diminishing returns, it represents an alternative worth discussing with a specialist.
20Clinical and Experimental Dermatology. Successful sirolimus treatment of spindle cell haemangiomas in a paediatric patient with Maffucci syndromeThe Epithelioid and Spindle Cell Hemangioma Variant
You may encounter the term “epithelioid and spindle cell hemangioma” in medical literature, and it is worth understanding how it relates to the standard spindle cell hemangioma. This variant contains a prominent population of epithelioid (plumper, rounder) endothelial cells in addition to the spindle-shaped ones. Recent clinicopathologic work supports the idea that epithelioid and spindle cell hemangioma is actually a morphologic variant of epithelioid hemangioma, a related but distinct vascular tumor, rather than a simple subtype of classic spindle cell hemangioma.
21The American Journal of Surgical Pathology. Epithelioid and Spindle Cell Hemangioma: Clinicopathologic Analysis of 18 Primary Bone and Soft Tissue Tumors Highlighting a Predilection for the Hands and Feet, Frequent Multicentricity, and Benign BehaviorThis distinction matters because it affects classification and potentially prognosis. Epithelioid hemangioma is itself benign but has different molecular drivers (most commonly FOS or FOSB gene rearrangements rather than IDH mutations). Where a given tumor falls on this spectrum can influence how a pathologist reports it and how a clinician monitors the patient. For most people with these lesions, the practical takeaway is the same: these are benign growths that do not metastasize but may recur locally and can be painful enough to warrant treatment.
When Spindle Cell Hemangioma Involves Bone
Most spindle cell hemangiomas are soft tissue tumors, but they can occasionally arise within bone, and this presentation can be especially confusing on imaging. Bone lesions may show destructive-looking changes with a soft tissue mass extending beyond the bone, which can mimic more aggressive tumors. The “soap bubble” pattern on CT and the enhancement characteristics on MRI, while somewhat suggestive, overlap with other bone tumors enough that biopsy is almost always needed for a definitive diagnosis.
22PubMed Central. Rare spindle cell hemangioma of bone: Case report and literature reviewBone involvement raises the differential diagnosis to include not just other vascular tumors but also giant cell tumor of bone, aneurysmal bone cyst, and metastatic disease. A pathologist examining the biopsy tissue and applying the right panel of immunohistochemical stains will usually settle the question. The behavior of spindle cell hemangioma in bone appears to be just as benign as in soft tissue, though the small number of reported cases means follow-up data are limited.
IDH-Targeted Therapies on the Horizon
The discovery of IDH mutations in spindle cell hemangioma raises an obvious question: could drugs targeting IDH, already approved for certain leukemias and brain tumors, work here? As of now, no published trials have tested IDH inhibitors specifically for spindle cell hemangioma. The rationale is there in theory, since the same molecular defect is being targeted, but the clinical need is different. Most patients with spindle cell hemangioma have a manageable condition that does not threaten their life, so the risk-benefit calculation for a systemic drug is higher than it would be for a cancer. Still, for patients with Maffucci syndrome who develop dozens of painful, recurrent tumors, an IDH-targeted approach could eventually offer a more rational treatment than repeated surgery. This is an area where the molecular genetics are well ahead of the clinical trials.