case_images: PMC10870065_01
case_images: Series of radiographs explicit the progression of pathological fracture at the proximal third of the humeral shaft. A, B: Initially frontal and later radiographs showed an acute oblique fracture of the proximal diaphysis of the left humerus with approximate half shaft width and lateral displacement of the distal fracture fragment. C, D: One-month follow-up radiograph again showed a mild interval improvement of alignment of the fragments. The distal component remains ununited and displaced laterally. E, F: Two-month follow-up radiograph showed unaltered alignment and positioning with ongoing mild impaction and apex medial/anterior angulation. No Significant interval callous formation. The union is not complete. There appears to be a moth-eaten pattern of the adjacent bony matrix concerning pathological fracture.
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case_images: PMC10870065_01_cureus-0016-00000052469-i01.jpg
case_images: FIG1
case_images: A radiographic examination revealed a mildly displaced spiral fracture in the upper third of the left humerus (Figures 1A, 1B). These images depicted a non-healing fracture and an increasingly irregular appearance suggestive of an underlying bone abnormality (Figures 1C-1F).
case_images: Left humeral aggressive bony lesion by CT, bone scan, and PET. A, B: Two separate CTs from the chest (part of metastatic workup) and during the biopsy, respectively, showed a non-united fracture with interval development of extraosseous/heterotopic ossification in two months. C-F: A whole-body skeletal survey was performed. Intense heterogeneous activity to the fracture involving proximal left humerus with questionable increased marrow density. The possible pathological fracture is again raised. G: The biopsy H/E consisted of a limited amount of material. The histological analysis of the biopsy sample revealed a spindle cell neoplasm characterized by moderate cytologic atypia (arrow), (10x). H: Biopsy H/E sample revealed a spindle cell neoplasm showed scattered mitotic figures (arrow), (inset 40x). I: Caldesmon immunohistochemical stain demonstrated strong diffuse positivity (10x). J, K: A near whole body scan (base of the skull to mid-thighs) FDG scan has been obtained supplemented with an uninfused low-dose CT for attenuation correction and anatomic localization. Intense activity to the large soft tissue mass surrounding the pathological fracture involving the proximal half of the left humerus as described consistent with a malignant process. It was in keeping with biopsy-approved osseous leiomyosarcoma..  FDG: Fluorodeoxyglucose
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case_images: PMC10870065_01_cureus-0016-00000052469-i02.jpg
case_images: FIG2
case_images: The initial CT chest examination confirmed a non-united humeral fracture with a suspected underlying lesion (Figures 2A, 2B). A whole-body bone scan was also conducted, showing intense and irregular activity at the site of the fracture, along with potential increased marrow density (Figures 2C-2F). At this juncture, the CT scan indicated a non-united fracture with suspected extraosseous ossification that had developed since the initial CT examination (Figures 2A, 2B).Under CT guidance and using coaxial technique, a 19 gauge introducer was placed into the soft tissue part of the lesion and 5 x 20 gauge core biopsies were obtained. The histological analysis of the biopsy sample revealed a spindle cell neoplasm characterized by moderate cytologic atypia (Figure 2G) and scattered mitotic figures (Figure 2H). The tumor cells exhibited widespread immunoreactivity for smooth muscle actin (SMA) and caldesmon (Figure 2I), while another muscle marker, desmin, tested negative. The PET scan demonstrated the absence of a primary pelvic mass but revealed high metabolic activity associated with a large soft tissue mass surrounding the pathologic fracture of the left humerus (Figures 2G-2H).
case_images: Further characterization of left humeral aggressive bony lesion. A-H: The known mass lesion about the proximal humerus is again demonstrated. It extends to involve the humeral head and extends inferiorly to the level of the mid-humeral shaft. This measures approximately 10.3 cm anterior-posterior by 8.3 cm medial-lateral by 15.9 cm craniocaudad. This replaces the marrow about the proximal humerus and there is associated soft tissue extension and pathologic fracturing. The lesion is predominately hypointense/isointense on T1-weighted sequences with some T1 hyperintense signal of the lateral deltoid region (A-D). The lesion is heterogeneous on fluid-sensitive sequences and there is an avid heterogeneous enhancement (E-H). This is in keeping with the known leiomyosarcoma.
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case_images: FIG3
case_images: The lesion predominantly exhibited hypointense to isointense signals on T1-weighted sequences, along with some T1 hyperintense signals in the lateral deltoid region, suggesting the presence of internal hemorrhages (Figures 3A-3D). On fluid-sensitive sequences, the lesion displayed heterogeneity, and there was pronounced and varied enhancement (Figures 3E-3H).
case_images: Gross and microscopic findings of perinephric tumor. A, B: Gross images showed a tumor arising from the shaft and head of the humerus (white arrow) demonstrating a white-tan, circumscribed soft, hemorrhagic, partly necrotic tumor, with smooth lobulated borders (white arrow). Areas of necrosis account for approximately 30% of the tumor. The mass extends through the articular surface of the humerus. C: 10x low power showing tumor infiltrating the existing bone as indicated in arrow. D: 10x low power showing tumor involving the soft tissue as indicated in arrow. E: 20x spindled cells in fascicular pattern as indicated in arrow. F: 20x tumor necrosis as indicated in the arrow. G: 40x mitotic figure as indicated in arrow. H: 40x tumor in the soft tissue with osteoid matrix as indicated in arrow.
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case_images: FIG4
case_images: Grossly, the tumor arose from the shaft and head of the humerus, displaying a well-defined soft, hemorrhagic, partly necrotic appearance with smooth, lobulated borders (Figures 4A, 4B). Under microscopic examination, the tumor was found to infiltrate the existing bone and involve the surrounding soft tissue (Figures 4C, 4D). Broad sections of the tumor exhibited characteristics akin to those seen in the initial biopsy tissue, featuring spindle cells with moderate cytological atypia and scattered mitoses (Figures 4E-4G). However, there were also areas within the tumor displaying the presence of osteoid matrix, a diagnostic hallmark of osteosarcoma (Figure 4H).