CASE 1. A fifty-seven-year-old man was admitted to the hospital because of a four-day history of worsening pain over the middle of the anterior aspect of the left shin. There was no history of trauma. Physical examination revealed local tenderness over the anteromedial aspect of the middle of the left tibial shaft. Routine laboratory data, including serum levels of alkaline phosphatase (196 international units per liter), calcium (9.5 milligrams per deciliter [2.37 millimoles per liter]), phosphorus (3.1 milligrams per deciliter [1.00 millimole per liter]), and uric acid (4.1 milligrams per deciliter [244 micromoles per liter]), were within normal limits. Radiographs showed an intracortical lytic lesion that was sharply circumscribed without a sclerotic margin in the anterior aspect of the middle of the left tibial shaft. The lesion displayed a type-IC geographic pattern11 (a well defined lytic lesion, more than one centimeter in its largest diameter, with disruption of the cortex) with internal calcification of the trabeculae in a vertical alignment and erosion of the cortical surface without periosteal reaction (Fig. 1-A). A computed tomographic scan confirmed the presence of an ovoid intracortical lesion of the tibia of low attenuation with small and spotty internal calcification (Fig. 1-B). Scintigraphy with technetium-99m polyphosphate demonstrated considerably increased uptake at the site of the tumor. A clinical diagnosis of osteoid osteoma was made, and the lesion was completely excised for histological examination. No reconstruction was necessary after the excision. Four years after the operation, the patient was well and had had no recurrence of the tumor.
On gross examination, the excisional biopsy sample revealed a bone specimen, twenty-five by three millimeters, that was macroscopically composed of cortical bone structure. Microscopically, the lesion consisted of anastomosing cavernous blood vessels, lined by endothelium, that occupied and expanded the haversian canals. This lesion conferred a trabecular appearance on the cortical compact bone. A pathological diagnosis of intracortical hemangioma was made.
CASE 2. A thirty-five-year old man who had a five-month history of a small, painful mass on the anterior surface of the left shin came to the hospital for treatment. The nodule, one centimeter in diameter, was covered by intact skin and had shown slow, progressive growth. The patient had had no previous injury in that area. Pain limited motion of the ankle during intense physical exercise. The patient was managed with analgesics and anti-inflammatory drugs for two weeks, but the symptoms persisted. Muscle strength, sensation, and vascular supply to the limb, as determined by evaluation of the pulses, were normal. The patient reported that he had had a cutaneous hemangioma in the neck that had been resected several years earlier. The serum levels of alkaline phosphatase (172 international units per liter), phosphorus (3.6 milligrams per diciliter [1.16 millimoles per liter]), calcium (9.8 milligrams per deciliter [2.45 millimoles per liter]), and uric acid (4.7 milligrams per deciliter [280 micromoles per liter]) were within normal limits.
Radiographs showed an ovoid intracortical lytic lesion in the anterior aspect of the tibia with no sclerotic margin but internal calcification of the trabeculae in a vertical alignment and a type-IB geographic pattern11 (a well defined lytic lesion, more than one centimeter in its largest diameter, with preservation of the cortex) (Fig. 2-A). There was no periosteal reaction. A computed tomographic scan revealed an ovoid lytic lesion with internal spotty calcification in the anterior cortex of the mid-part of the tibial shaft. A characteristic so-called intralesional wire-netting calcification pattern that consisted of a honeycomb reticular pattern and encompassed the vascular channels was prominent (Fig. 2-B). A magnetic resonance image, without contrast material, showed an intracortical ovoid lesion with irregular edges and a hyperintense signal with internal, hypointense septa on T1 and T2-weighted sequences (Fig. 2-C). The hyperintensity was brighter on the T2-weighted image than it was on the T1-weighted image. Scintigraphy with technetium-99m polyphosphate demonstrated considerably increased uptake at the site of the tumor. On the basis of the radiographic findings, the lesion was considered to be an osteoid osteoma. A complete resection of the tumor was performed. No reconstruction was necessary after the excision. One year postoperatively, the patient was well, had full motion of the knee and ankle without pain, and had had no recurrence of the tumor.
The excisional biopsy sample consisted of a cortical bone specimen that was thirty by three millimeters. Histological analysis showed expanded haversian canals occupied by a proliferation of dilated cavernous vessels filled with bloody material. The vessels had a thin wall with an endothelial lining (Fig. 2-D). The growth of the tumor had conferred a trabecular appearance on the cortical compact bone (Fig. 2-E). A thin layer of reactive woven bone was evident on the exterior of the tibial cortex. Intracortical hemangioma was diagnosed.
Hemangioma of bone is an osseous neoplasm accounting for less than 1 percent of bone tumors (eighty of 8542)4. Biopsies are rarely done. Dorfman et al. found that seventeen (71 percent) of twenty-four hemangiomas occurred in the bodies of the vertebrae and in the skull6. Lesions in the spine have a coarse, vertical trabecular pattern with a so-called corduroy appearance on radiographs22. A computed tomographic scan displays a characteristic polka-dot pattern15,22. Radiographically, cranial hemangiomas have the appearance of cortical expansion with a radiating trabecular pattern, or the so-called sunburst sign15,22. Lesions in the long bones, which are much less frequent, generally affect the medullary cavity of the metaphysis and provoke a bubbly lysis of bone or a coarsely lobulated appearance22.
Hemangiomas that originate from within the cortex of the bone without involvement of the medullary cavity are rare. To our knowledge, only nine such lesions have been well documented in the literature6,5,10,15,18,19,21. Most were misdiagnosed, frequently as an osteoid osteoma, on the basis of radiographic findings. Seven of the nine hemangiomas were in the tibial diaphysis, one was in the distal end of the ulna, and one was in the middle of the femoral shaft (Table I). The mean age of the patients was thirty-six years (range, sixteen to fifty-four years). Four were women, and five were men. Two patients were asymptomatic; the lesion was discovered during routine examination. Three patients had pain. Symptoms were not mentioned for the remaining four. The lesions in the present case report occurred in the anterior aspect of the tibial diaphysis of two men. One man was fifty-seven years old, and the other was thirty-five. Both men had pain in that area, and one had limited motion during intense physical exercise.
The previously reported hemangiomas had two radiographic patterns: (1) localized cortical thickening with a central lytic nidus (six patients)5,6,18,19 and (2) a radiolucent lesion without sclerotic edges (three patients)10,15,21. One of the three radiolucent lesions also had intralesional calcification with vertical striations15. A computed tomographic scan was made for only two patients10,15. The hemangioma reported by Kenan et al. was a localized lucent lesion with a central calcified nidus10. Murphey et al. observed intracortical vascular channels that ran longitudinally and transversely15. Magnetic resonance imaging was performed for two patients15,19. Seeff et al. described an intermediate signal intensity on T1 and T2-weighted sequences19. Using contrast material, Murphey et al. observed a high signal intensity on T1 and T2-weighted sequences of a lesion with a relatively slow flow of blood. Plain radiographs of our patients showed an intracortical, lytic, and well demarcated lesion with characteristic calcification of the trabeculae in a vertical alignment. There were no sclerotic margins or periosteal reactions. Computed tomographic scans of our patients demonstrated a lytic lesion with spotty internal calcification, or a so-called wirenetting appearance. The magnetic resonance image of the second patient revealed a hyperintense signal with internal hypointense septa on T1 and T2-weighted sequences; the hyperintensity was brighter on the T2 image than it was on the T1 image. This finding suggests a lesion with a high hematological content.
Histologically, the intracortical hemangiomas in the previous and present reports consisted of a capillary, arteriovenous, or, more frequently, cavernous hemangioma located within the cortical bone without an adjacent soft-tissue mass. Nevertheless, there is sometimes clinical and radiographic overlap between periosteal and intracortical hemangiomas5. This phenomenon led Devaney et al. to call these tumors "surfaced-based hemangiomas of bone."5 The extensive intracortical vascular proliferation with reabsorption and tunneling of haversian canals characteristically transforms the compact cortical bone into trabecular-like bone. Thus, the radiographic images of these tumors are comparable with those of hyperparathyroidism with cortical bone involvement17 even though the lesions differ etiologically and pathogenically.
The radiographic appearance of intracortical hemangioma is similar to that of osteoid osteoma. Both tumors are located within cortical bone and are generally in the diaphysis of a long bone7,12. Radiographs of both types of lesions may show lysis with a central homogeneous nidus surrounded by a sclerotic bone margin. However, the lytic variant of intracortical hemangioma has characteristic intracortical calcification of the trabeculae in a vertical alignment. To our knowledge, these specific features, which were clearly observed in our two patients, have been mentioned only once in the literature, by Murphey et al.15 in their legend of Figure 6. Perhaps these features, as well as the spotty or wire-netting pattern that is seen on computed tomographic scans and the hyperintense signal with internal hypointense septa that is seen on T1 and T2-weighted magnetic resonance images, were overlooked in the other previously reported cases of radiolucent intracortical hemangioma.
We believe that a finding of calcification of the trabeculae in a vertical alignment, observed in different radiographic projections and with different radiographic projections and with different radiographic techniques, is extremely useful in the radiographic diagnosis of intracortical hemangioma and in the differentiation of the lesion from osteoid osteoma1. An anomaly of intraosseous venous drainage in a patient who has pretibial varices2 should also be considered during the radiographic differential diagnosis of intracortical hemangioma. Intracortical hemangioma does not have pretibial varices. In the literature, lesions such as osteofibrous dysplasia3,16, fibrous cortical defects14, adamantinoma9, solitary cortical bone metastasis8, and Brodie abscess13 have also been included in the differential diagnosis. However, we believe that these conditions have obvious radiographic and clinical differences that distinguish them from intracortical hemangioma.
In summary, this report is, to our knowledge, the first detailed description of the conventional radiographic, computed tomographic, and magnetic resonance imaging features of intracortical hemangioma of the tibial diaphysis. We consider the characteristic findings that we described to be specific enough to allow an accurate radiographic diagnosis of this condition and to differentiate it from other intracortical lesions.