Skeletal fluorosis and instant tea.
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Bone and Bones↗
Biomedical subjects
Francis H Gannon
Publications and source records attributed to Francis H Gannon.
Neonatal lethal osteochondrodysplasia with low serum levels of alkaline phosphatase and osteocalcin.
Neonatal lethal skeletal dysplasias are rare and typically involve thoracic malformations and severe limb shortening. We report on a newborn boy manifesting an osteochondrodysplasia associated with fatal respiratory insufficiency who had normal lung volumes and extremity lengths. His disorder featured aberrant skeletal patterning and defective ossification including a severely osteopenic skull, apparent absence of clavicles, and clefting of the mandible and vertebrae. Serum alkaline phosphatase and osteocalcin levels were markedly low. Biochemical studies suggested parathyroid insufficiency probably from critical illness. Histopathology at autopsy excluded impaired mineralization of skeletal matrix, but endochondral bone formation appeared disorganized with growth plate clustering of chondrocytes in hypertrophic zones and in zones of provisional calcification. Parathyroid glands were not found. Despite features of two distinctive heritable entities, hypophosphatasia and cleidocranial dysplasia, the cumulative findings did not match either condition, and no mutations were found in either the tissue nonspecific ALP isoenzyme or core-binding factor genes, respectively, or in the genes encoding osteocalcin or the osteoblast transcription factor osterix. This patient could represent the extreme of cleidocranial dysplasia (a disorder not always associated with structural mutation in core-binding factor A1), but more likely he defines a unique osteochondrodysplasia disrupting both intramembranous and endochondral bone formation.
Alkaline Phosphatase↗
Imaging of periosteal osteosarcoma: radiologic-pathologic comparison.
PURPOSE: To review the imaging appearance of periosteal osteosarcoma, with pathologic comparison. MATERIALS AND METHODS: Data for 40 pathologically confirmed periosteal osteosarcomas were retrospectively reviewed. Patient demographic data were recorded, and radiographs (n = 40), bone scintigrams (n = 10), angiograms (n = 2), and computed tomographic (CT) (n = 11) and magnetic resonance (MR) (n = 12) images were evaluated for lesion location and size, cortical changes, marrow involvement, and intrinsic characteristics by two musculoskeletal radiologists, with agreement by consensus. Pathology reports were reviewed for presence and predominance of histologic components (fibrous, chondroid, and osteoid), tumor grade, and marrow involvement. RESULTS: There were 25 male (62%) and 15 female (38%) patients with an age range of 10-37 years (average age, 20 years). The most frequent lesion locations were the diaphysis of the tibia (16 patients) or of the femur (15 patients). Radiographs showed a broad-based soft-tissue mass that was attached to the cortex (all patients) and showed cortical thickening (33 patients), cortical scalloping/erosion (37 patients), and/or perpendicular periosteal reaction (38 patients) extending into the soft-tissue mass. Soft-tissue masses were well defined in 91%-100% of cases and surrounded a median of 50%-55% of the cortex. Lesions commonly showed low attenuation at CT (10 patients) and high signal intensity on T2-weighted MR images (10 patients), reflecting the high water content of these largely chondroblastic lesions. Focal areas of adjacent marrow replacement were common at MR imaging (nine patients) but represented reactive changes unless they were in direct continuity with the overlying soft-tissue mass (this was rare, occurring in only one patient, and represented marrow invasion). Review of pathology reports revealed that all lesions contained chondroid tissue, which predominated in 34 patients. CONCLUSION: The radiologic appearance of periosteal osteosarcoma is a broad-based surface soft-tissue mass causing extrinsic erosion of thickened underlying diaphyseal cortex and perpendicular periosteal reaction extending into the soft-tissue component. Reactive marrow changes are commonly seen at MR imaging, but true marrow invasion is rare.
Adolescent↗
Ossifying fibroma of the jaw.
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Fibroma, Ossifying↗
Primitive adult hematopoietic stem cells can function as osteoblast precursors.
Osteoblasts are continually recruited from stem cell pools to maintain bone. Although their immediate precursor is a plastic-adherent mesenchymal stem cell able to generate tissues other than bone, increasing evidence suggests the existence of a more primitive cell that can differentiate to both hematopoietic and mesenchymal cells. We show here that the "side population" (SP) of marrow stem cells, defined by their ability to rapidly expel a DNA-binding dye and to regenerate the hematopoietic compartment, can differentiate to osteoblasts through a mesenchymal intermediate. When transplanted into lethally irradiated mice, single gene-marked murine SP cells reconstituted depleted osteoprogenitor pools, such that a large proportion of the osteogenic cells in the epiphysis of long bone carried the donor SP cell marker. These findings suggest that the developmental capacity of SP cells is not restricted to the hematopoietic lineages but extends to osteogenic differentiation. This property not only elucidates a previously unrecognized step in osteoblast development, but also has intriguing implications for the use of SP cells in clinical orthopedics and stem cell-based disorders of bone.
Animals↗
Telangiectatic osteosarcoma: radiologic-pathologic comparison.
PURPOSE: To describe the imaging characteristics of a large series of telangiectatic osteosarcomas with pathologic findings for comparison. MATERIALS AND METHODS: The authors retrospectively reviewed 40 pathologically confirmed telangiectatic osteosarcomas. Patient demographics and images from radiography (n = 36), bone scintigraphy (n = 17), angiography (n = 4), computed tomography (CT) (n = 25), and magnetic resonance (MR) imaging (n = 27) were evaluated by three authors in consensus for lesion location, size, and intrinsic characteristics. There were 27 men (68%) and 13 women (32%) in the study, with an age range of 4-83 years (mean age, 24 years). RESULTS: Lesions frequently affected the femur, tibia, and humerus. Radiographs showed geographic bone lysis, a wide zone of transition, and matrix mineralization. CT demonstrated low attenuation, MR demonstrated high signal intensity on T2-weighted images, and both demonstrated hemorrhage, which simulated the appearance of aneurysmal bone cyst. Viable sarcomatous tissue surrounding hemorrhagic and/or necrotic regions was best seen at contrast material-enhanced CT and MR imaging, with thick peripheral, septal, and nodular enhancement in all cases. Subtle matrix mineralization in this viable tissue was best seen at CT. An associated soft-tissue mass was also seen in 19 of 25 cases (76%) at CT and in 24 of 27 cases (89%) at MR imaging. CONCLUSION: CT and MR imaging findings of telangiectatic osteosarcoma often include thick nodular tissue (and matrix mineralization at CT) in a largely hemorrhagic and/or necrotic osseous lesion with an associated soft-tissue mass, which allows distinction from aneurysmal bone cyst.
Adolescent↗
Stromal cells of fibrodysplasia ossificans progressiva lesions express smooth muscle lineage markers and the osteogenic transcription factor Runx2/Cbfa-1: clues to a vascular origin of heterotopic ossification?
Fibrodysplasia ossificans progressiva (FOP) is a rare heritable genetic disorder, which is characterized pathologically by sporadic episodes of explosive growth of mesenchymal cells in skeletal muscle followed by cellular differentiation to heterotopic bone through an endochondral process. This study examined the histological origin and differentiation state of stromal cells in early FOP lesions and investigated the association between the phenotype of these FOP cells and bone formation. Interestingly, FOP lesional stromal cells were found to display characteristics of the smooth muscle (SM) cell lineage and are therefore potentially of vascular origin. These cells co-express multiple SM lineage markers along with multiple proteins associated with bone formation including the obligate osteogenic transcription factor Runx2/Cbfa-1. It is hypothesized that the stromal cells of early FOP lesions may be locally recruited vascular cells or cells of the bone marrow stroma and that these cells maintain the potential (given the correct environmental stimuli) to differentiate along an endochondral ossification pathway.
Biopsy↗
Malignant giant cell tumor of the sphenoid.
Malignant giant cell tumors (MGCTs) of the sphenoid sinus are extremely rare neoplasms. They are challenging to diagnose and difficult to treat because of their skull base location. To the best of our knowledge, we report the first case of a primary MGCT of the sphenoid arising in a patient with Paget's disease. A 77-year-old man presented with epistaxis and a history of Paget's disease. There was normal cranial nerve function although radiographic images disclosed a large mass centered in the sphenoid sinus and extending into the ethmoid and maxillary sinuses. Excisional biopsy revealed a MGCT composed of a cellular stroma with increased mitotic activity and necrosis with giant cells present throughout. Additional therapy was declined and the patient died with disease 7 months later. Because of their rarity, no treatment guidelines exist for the management of MGCTs of the sphenoid. We discuss both the diagnostic and therapeutic considerations based on a review of the pertinent literature.
Aged↗
Reconstruction of the immature craniofacial skeleton with a carbonated calcium phosphate bone cement: interaction with bioresorbable mesh.
Calcium phosphate cements have been recently introduced for use in craniofacial reconstruction. In the clinical setting, however, pulsations of the underlying brain and dura may interfere with the crystallization of these cements, thereby rendering their use in cranioplasty problematic. To circumvent such problems, many clinicians have interposed synthetic resorbable plates or mesh between the dura and the cement. At the present time, however, little is known about the influence of such materials or their breakdown products on the fate of calcium phosphate cements. The specific aim of this project was to evaluate the biocompatibility, osteoconductivity, and remodeling capacity of a calcium phosphate cement after implantation into experimental calvarial defects when combined with a resorbable mesh underlay. Four 10-mm diameter full-thickness calvarial defects (two frontal, two parietal) were created in each of six 3-week-old Yorkshire pigs. The defects were treated as follows: 1) empty control, 2) macroporous polylactic acid (70/30 L/DL polylactic acid [PLA]) mesh, 3) Norian CRS calcium phosphate cement, and 4) Norian CRS over PLA mesh underlay. Animals were divided into two groups. Half of the animals were killed 30 days after surgery, and half were killed 180 days after surgery, and the graft recipient sites were examined histologically. At 30 days, minimal bone ingrowth was observed in untreated calvarial defects or in those that were treated with PLA plates alone. Defects treated with the cement alone demonstrated a modest amount of new woven bone deposition, primarily at the periphery of the implants. Defects treated with calcium phosphate cement over PLA mesh underlays were characterized by remodeling and woven bone deposition at 30 days, with complete or near-complete osseous bridging of the ectocranial implant surfaces. Progressive bone ingrowth was noted in all defects at 180 days, with near-complete replacement of all Norian CRS implants by host bone. The PLA mesh remained incompletely resorbed at 180 days. No inflammatory response to the implants was observed at either time point. Calcium phosphate cement may be safely used for craniofacial reconstruction in the presence of PLA implants without compromise to its biocompatibility, osteoconductivity, or remodeling capacity.
Absorbable Implants↗
Mesenchymal chondrosarcoma of the sinonasal tract: a clinicopathological study of 13 cases with a review of the literature.
OBJECTIVES/HYPOTHESIS: Mesenchymal chondrosarcoma of the sinonasal tract is a rare, malignant tumor of extraskeletal origin. Isolated cases have been reported in the English literature, with no large series evaluating the clinicopathological aspects of these tumors. STUDY DESIGN: Retrospective review. METHODS: Thirteen patients with sinonasal mesenchymal chondrosarcoma were retrieved from the Otorhinolaryngologic-Head and Neck Registry of the Armed Forces Institute of Pathology. RESULTS: Nine women and 4 men (age range, 11 to 83 y; mean age, 38.8 y) presented with nasal obstruction (n = 8), epistaxis (n = 7), or mass effect (n = 4), or a combination of these. No patients reported prior head and neck irradiation. The maxillary sinus was the most common site of involvement (n = 9), followed by the ethmoid sinuses (n = 7) and the nasal cavity (n = 5). Tumors had an overall mean size of 5.1 cm. Microscopically, the tumors displayed a small, blue, round cell morphology appearance arranged in a hemangiopericytoma-like pattern with foci of cartilaginous matrix. All cases were managed by surgery with adjuvant radiation therapy (n = 4) and/or chemotherapy (n = 3). The overall mean survival was 12.1 years, although five of six patients who developed local recurrences died of disease (mean survival, 6.5 y). Six patients were alive and disease free (mean survival, 17.3 y), and two patients were lost to follow-up. CONCLUSIONS: Mesenchymal chondrosarcoma of the sinonasal tract is an aggressive tumor with a predilection for young women. The pattern of growth and scarcity of cartilaginous matrix result in frequent misdiagnosis. Recurrence develops in approximately one-third of patients and seems to predict a poor prognosis. Aggressive, exenterative surgery combined with adjuvant therapy appears to yield the best clinical outcome.
Adolescent↗
Use of a chimeric adenovirus vector enhances BMP2 production and bone formation.
Recombinant adenoviral vectors have potential for the treatment of a variety of musculoskeletal defects and such gene therapy systems have been a recent research focus in orthopedic surgery. In studies reported here, two different adenovirus vectors have been compared for their ability to transduce human bone marrow mesenchymal stem cells (hBM-MSCs) and elicit bone formation in vivo. Vectors consisted either of standard adenovirus type 5 (Ad5) vector or a chimeric adenovirus type 5 vector that contains an adenovirus type 35 fiber (Ad5F35), which has been recently demonstrated to bestow a different cellular tropism, and a complete cDNA encoding human bone morphogenetic 2 (BMP2). Studies were also conducted to compare the transduction efficiency of these vectors using enhanced green fluorescent protein (GFP). hBM-MSCs transduced with Ad5F35 vectors had higher levels of transgene expression than those transduced with Ad5 vectors. The results also demonstrate that hBM-MSCs lack the coxsackie-adenovirus receptor (CAR), which is responsible for cellular adsorption of Ad5. Therefore, the data suggest that Ad5 virus adsorption to hBM-MSCs is inefficient. Ad5BMP2- or Ad5F35BMP2-transduced hBM-MSCs were also compared in an in vivo heterotopic bone formation assay. Mineralized bone was radiologically identified only in muscle that received the Ad5F35BMP2 transduced hBM-MSCs. In summary, Ad5F35BMP2 can efficiently transduce hBM-MSCs leading to enhanced bone formation in vivo.
Adenoviridae↗
Chondrosarcoma of the larynx: a clinicopathologic study of 111 cases with a review of the literature.
Chondrosarcomas of the larynx are rare tumors accounting for about 0.5% of all laryngeal primary tumors. A total of 111 laryngeal chondrosarcoma cases, diagnosed between 1970 and 1997, were retrieved from the Otorhinolaryngic-Head & Neck Tumor Registry of the Armed Forces Institute of Pathology. There was a 3.6:1 male/female ratio of patients 25-91 years of age (mean, 64.4 years). Patients presented most frequently with hoarseness (n = 72 patients) present for a mean of 28.2 months. The majority of tumors involved the cricoid cartilage (n = 77) with a mean size of 3.5 cm. All tumors were invasive and malignant by radiology and/or histology (into bone within the ossified laryngeal cartilages in 52 tumors). Most tumors were low-grade lesions: grade 1 (n = 51), grade 2 (n = 54); there were six grade 3 tumors. An associated benign chondroma with (n = 41 tumors) or without ischemia (n = 24 tumors) was noted. All patients had surgery and five had radiation therapy. Wide excision or voice-sparing surgery was used in 73 patients, whereas 37 patients had a laryngectomy. Recurrences occurred in 20 (18%) patients, 10 of whom underwent salvage laryngectomy. At the last follow-up, 102 patients had no evidence of disease (alive or dead, mean 11.2 years) and five patients had evidence of disease (alive, one patient, 6.5 years; dead, four patients, mean 6.4 years). The six patients with high-grade chondrosarcoma were all without disease at the last follow-up (mean, 15.1 years). There was no difference in clinical outcome based on grade (p = 0.210), location (p = 0.078), or treatment (p = 0.607) but was worse for patients with a myxoid-type chondrosarcoma (p = 0.044). Primary laryngeal chondrosarcomas are typically low- to moderate-grade lesions involving the cricoid cartilage, frequently associated with a chondroma. They usually portend an excellent overall long-term prognosis with initial conservative voice-sparing surgery.
Adult↗
Repair of the immature craniofacial skeleton with a calcium phosphate cement: quantitative assessment of craniofacial growth.
The potential for growth restriction has limited the use of alloplastic materials for reconstruction of the growing craniofacial skeleton. A calcium phosphate cement that has been introduced recently for craniofacial reconstruction crystallizes in situ into a substance that resembles more closely the mineral phase of bone, thereby offering the potential for enhanced bioresorption and osteoconductivity. The purpose of these experiments was to assess quantitatively craniofacial growth after reconstruction of frontal craniectomy defects in skeletally immature animals with this calcium phosphate bone mineral substitute. To simulate the calvarial defects that result from unilateral fronto-orbital advancement procedures, unilateral frontal bone flaps were removed in 3-week-old female Yorkshire piglets. The bone flaps were trimmed medially and posteriorly, and were then reattached to the supraorbital ridge. The resulting 5-mm gap between the frontal bone flap and the native bone was either filled with Norian CRS bone cement (N = 3) or left empty (N = 3). After 90 days, the animals were killed and the skulls were harvested and cleared. Direct craniometric measurements were performed on the prepared dry skulls to assess craniofacial growth in all dimensions. Extensive remodeling was observed within defects treated with the calcium phosphate cement, with complete or near-complete replacement of the cement by host bone, resulting in a solid bony union. Direct craniometric measurements revealed no differences in craniofacial growth in any dimension between the operated and unoperated sides of the cranium in either group. These studies demonstrate that craniofacial growth is not restricted after reconstruction of frontal craniectomy defects with carbonated calcium phosphate cement in skeletally immature animals. The remodeling capacity of this material offers promise for its safe use in reconstruction of the growing calvarium.
Animals↗
Dedifferentiated chondrosarcomas of the larynx: a report of two cases and review of the literature.
OBJECTIVE: To analyze the long-term clinical outcome of dedifferentiated chondrosarcoma or chondrosarcoma with additional malignant mesenchymal component (CAMMC) of the larynx and compare the results with those of axial chondrosarcomas. STUDY DESIGN/METHODS: Two patients with CAMMC of the larynx (0.03%) were retrospectively identified within the archives of the Armed Forces Institute of Pathology between 1970 and 2001. We compared the clinical and histologic features of these two cases with those reported in the English literature (Medline 1966-2001) (Table I). RESULTS: Patient no. 1 was a 67-year-old man who presented with a 12-month history of hoarseness and was found to have a 4-cm mass involving the cricoid cartilage. Enucleation was performed and histologically demonstrated a dedifferentiated chondrosarcoma. Without additional intervention, the patient died after 136 months without evidence of disease. Patient no. 2 was a 41-year-old man who also presented with a 12-month history of hoarseness and dysphagia and was found to have a 5-cm mass involving the cricoid cartilage. A total laryngectomy was performed for the dedifferentiated chondrosarcoma. He is alive without evidence of disease at last contact (91 mo). CONCLUSION: CAMMC of the larynx are rare tumors but have a better prognosis than their axial counterparts (mean, 6 mo). Initial voice-sparing surgery can be followed with more aggressive surgery if recurrences develop.
Adult↗
Craniosynostosis and altered patterns of fetal TGF-beta expression induced by intrauterine constraint.
Recent work has demonstrated that fusion of the calvarial sutures is mediated by locally elaborated soluble growth factors, including the transforming growth factor-betas (TGF-betas), leading some to speculate that external biomechanical forces play little role in suture development. Clinical evidence has long suggested, however, that fetal head constraint may play a critical role in the pathogenesis of many cases of nonsyndromic craniosynostosis. The purpose of these experiments was to test the hypothesis that intrauterine constraint leads to an alteration in normal patterns of TGF-beta expression and that these alterations are associated with craniosynostosis. Fetal constraint was induced by allowing C57Bl/6 murine fetuses to grow for 2.5 days beyond the normal 20-day gestation by performing uterine cerclage on the eighteenth day. Cranial suture morphology was examined in hematoxylin and eosin-stained sections and in cleared whole-mount specimens, double stained with alizarin red S and Alcian blue. Expression patterns of TGF-beta1 and TGF-beta3 were examined by immunohistochemical techniques. Gross and microscopic examination of the cranial sutures of 17 constrained fetuses revealed changes that ranged from narrowing to complete osseous obliteration of the coronal and squamosal sutures. All sutures of 14 nonconstrained control pups remained patent. Fetal head constraint was associated with increased TGF-beta1 immunoreactivity within the new bone and the underlying dura when compared with nonconstrained age-matched controls. TGF-beta3 immunoreactivity was associated with the dura underlying patent, nonconstrained sutures, whereas constraint-induced synostosis was characterized by down-regulation of dural TGF-beta3 expression. These experiments confirm the ability of intrauterine constraint to induce premature fusion of the cranial sutures and provide evidence that intrauterine head constraint induces the expression of osteogenic growth factors in fetal calvarial bone and the underlying dura.
Animals↗
From the archives of the AFIP. Radiologic spectrum of Paget disease of bone and its complications with pathologic correlation.
Paget disease of bone is a common disorder affecting approximately 3%-4% of the population over 40 years of age. The pathologic abnormality in Paget disease is excessive and abnormal remodeling of bone. Three pathologic phases have been described: the lytic phase (incipient-active), in which osteoclasts predominate; the mixed phase (active), in which osteoblasts cause repair superimposed on the resorption; and the blastic phase (late-inactive) in which osteoblasts predominate. Radiographic appearance of Paget disease reflects these pathologic changes and is often characteristic. Initially, there is osteolysis, particularly affecting the skull (osteoporosis circumscripta) and subchondral long bones, with subsequent development of trabecular and cortical thickening and enlargement of bone in the mixed phase of the disease. Finally, areas of sclerosis may develop in the blastic phase. Frequent sites of involvement include the skull (25%-65% of cases), spine (30%-75%), pelvis (30%-75%), and proximal long bones (25%-30%). Bone scintigraphy typically demonstrates marked increased uptake of radionuclide in all phases of Paget disease. Computed tomography and magnetic resonance imaging often show changes similar to those seen radiographically in noncomplicated Paget disease with maintenance of yellow marrow. Complications of Paget disease include the effects of osseous weakening (deformity and fracture), arthritis, neurologic symptoms, and neoplastic involvement. Sarcomatous transformation is the most feared complication, occurring in approximately 1% of cases, and is seen on images as focal bone destruction extending through the cortex with an associated soft-tissue mass. Recognition of the radiologic spectrum of the appearances of Paget disease usually allows prospective diagnosis and differentiation of its associated complications, which helps guide therapy and improve patient management.
Diagnostic Imaging↗
From the archives of the AFIP: imaging of primary chondrosarcoma: radiologic-pathologic correlation.
Chondrosarcoma is a malignant tumor that produces cartilage matrix, and lesions that arise de novo are called primary. Primary chondrosarcoma is the third most common primary malignant tumor of bone, constituting 20%-27% of all primary malignant osseous neoplasms. There are numerous types of primary chondrosarcomas, including conventional intramedullary, clear cell, juxtacortical, myxoid, mesenchymal, extraskeletal, and dedifferentiated. The conventional intramedullary chondrosarcoma is the most frequent type, and it most commonly involves the long bones or pelvis in up to 65% of cases. Although the pathologic appearance varies with specific lesion type, chondrosarcomas grow with lobular type architecture, and these hyaline cartilage nodules demonstrate high water content and peripheral enchondral ossification. Imaging features directly reflect this pathologic appearance, and the various subtypes often show distinctive features. Radiographic findings often suggest the diagnosis of chondrosarcoma because of identification of typical "ring-and-arc" chondroid matrix mineralization (representing the enchondral ossification) and aggressive features of deep endosteal scalloping and soft-tissue extension. These latter features are usually best assessed, as is lesion staging, with computed tomography (CT) or magnetic resonance (MR) imaging. CT is optimal to detect the matrix mineralization, particularly when it is subtle or when the lesion is located in anatomically complex areas. Both CT and MR imaging depict the high water content of these lesions as low attenuation and very high signal intensity with T2-weighting, respectively. Understanding and recognizing the spectrum of appearances of the various types of primary chondrosarcoma allow improved patient assessment and are vital for optimal clinical management including diagnosis, biopsy, staging, treatment, and prognosis.
Academies and Institutes↗
From the archives of the AFIP: benign musculoskeletal lipomatous lesions.
Benign lipomatous lesions involving soft tissue are common musculoskeletal masses that are classified into nine distinct diagnoses: lipoma, lipomatosis, lipomatosis of nerve, lipoblastoma or lipoblastomatosis, angiolipoma, myolipoma of soft tissue, chondroid lipoma, spindle cell lipoma and pleomorphic lipoma, and hibernoma. Soft-tissue lipoma accounts for almost 50% of all soft-tissue tumors. Radiologic evaluation is diagnostic in up to 71% of cases. These lesions are identical to subcutaneous fat on computed tomographic (CT) and magnetic resonance (MR) images and may contain thin septa. Lipomatosis represents a diffuse overgrowth of mature fat affecting either subcutaneous tissue, muscle or nerve, and imaging is needed to evaluate lesion extent. Lipoblastoma is a tumor of immature fat occurring in young children, and imaging features may reveal a mixture of fat and nonadipose tissue. Angiolipoma, myolipoma, and chondroid lipoma are rare lipomatous lesions that are infrequently imaged. Spindle cell and pleomorphic lipoma appear as a subcutaneous lipomatous mass in the posterior neck or shoulder, with frequent nonadipose components. Hibernoma appears as a lipomatous mass with serpentine vascular elements. Benign lipomatous lesions affecting bone, joint, or tendon sheath include intraosseous lipoma, parosteal lipoma, liposclerosing myxofibrous tumor, discrete lipoma of joint or tendon sheath, and lipoma arborescens. Intraosseous and parosteal lipoma have a pathognomonic CT or MR appearance, with fat in the marrow space or on the bone surface, respectively. Liposclerosing myxofibrous tumor is a rare intermixed histologic lesion commonly located in the medullary canal of the intertrochanteric femur. Benign lipomatous lesions may occur focally in a joint or tendon sheath or with diffuse villonodular proliferation in the synovium (lipoma arborescens) and are diagnosed based on location and identification of fat. Understanding the spectrum of appearances of the various benign musculoskeletal lipomatous lesions improves radiologic assessment and is vital for optimal patient management.
Adolescent↗