Pelvic solitary plasmacytoma: computed tomography and magnetic resonance imaging findings with histopathologic correlation

Primary Osseous Malignancies of the Spine

Malignant primary vertebral tumours comprise an uncommon group of primary bone malignancies that can pose a diagnostic and therapeutic challenge. The most frequently encountered malignant primary vertebral tumours include chordoma, chondrosarcoma, Ewing sarcoma and osteosarcoma. These tumours often present with nonspecific symptoms, such as back pain, neurologic deficits and spinal instability, which can be confused for the more commonly encountered mechanical back pain and may delay their diagnosis and treatment. Imaging, including radiography, computed tomography (CT) and magnetic resonance imaging (MRI) is crucial for diagnosis, staging, treatment planning and follow-up. Surgical resection remains the mainstay of treatment for malignant primary vertebral tumours, but adjuvant radiotherapy and chemotherapy may be necessary for achieving complete tumour control depending on the type of tumour. In recent years, advances in imaging techniques and surgical approaches, such as en-bloc resection and spinal reconstruction, have improved the outcomes for patients with malignant primary vertebral tumours. However, the management can be complex due to the anatomy involved and the high morbidity and mortality associated with surgery. The different types of malignant primary vertebral lesions will be discussed in this article with an emphasis on the imaging features.

Differentiation of multiple myelomas from osteolytic bone metastases: Diagnostic value of tumor homogeneity on Contrast-Enhanced CT

OBJECTIVES

To investigate the diagnostic value of tumor homogeneity on contrast-enhanced (CE) computed tomography (CT) to differentiate multiple myeloma (MM) from osteolytic bone metastases (Mets).

METHODS

This retrospective study included patients who were diagnosed with MM or Mets and had multiple (≥2) osteolytic bone tumors on pre-treatment CE-CT. Intratumoral homogeneity was assessed by coefficient of variation (CV, ratio of standard deviation to mean) of the density of a single lesion (CV-lesion). Intertumoral homogeneity was assessed as the CV of the densities of multiple lesions in one patient (CV-patient). A classification model was built from CT parameters using classification and regression tree (CART) analysis. Diagnostic performance of the model was evaluated using C-statistics.

RESULTS

A total of 272 lesions (81 MM and 191 Mets) of 105 patients were analyzed. The mean CV-lesion and CV-patient of MM were significantly lower than those of Mets: 0.17 vs 0.26 for CV-lesion (p = 0.005) and 0.16 vs 0.23 for CV-patient (p = 0.013). Thickened struts were more common in MM than in Mets (49.1% vs 12.8%, p ≤ 0.001). In CART analysis, CV-lesion was the first partitioning predictor, followed by thickened struts and by CV patient. The CART model could distinguish MM from Mets in both the model development cohort (C-statistic: 0.843) and the temporal validation cohort (0.721, 0.686, and 0.686 for three reviewers, respectively).

CONCLUSIONS

MM showed intratumoral and intertumoral homogeneity compared with Mets on CE-CT. The combination of CV-lesion and CV-patient can be helpful to radiologists in differentiation of MM from Mets.

ADVANCES IN KNOWLEDGE

Our study showed that MM had intratumoral and intertumoral homogeneity compared with Mets on contrast-enhanced CT.

Untreated plasmacytoma of bone containing macroscopic intralesional fat and mimicking intraosseous lipoma: A case report and review of the literature

Solitary plasmacytoma is a rare form of plasma cell neoplasm defined by local neoplastic accumulation of monoclonal plasma cells in the absence of systemic proliferative plasma cell disease. In this case report, a 65-year-old female with remote past medical history of papillary thyroid cancer presented with shoulder pain and radiographs showing an aggressive osteolytic lesion presumed to represent an osseous metastasis. The subsequent MRI and CT examinations demonstrated diffuse intralesional macroscopic fat without a nonlipogenic soft tissue component or focal, nodular mass-like enhancement. The presence of macroscopic fat in an untreated osseous lesion suggested a benign lesion with the favored diagnosis an intraosseous lipoma with non-displaced pathological fracture. Therefore, the decision was made to forego image-guided percutaneous biopsy and instead proceed directly to open surgical biopsy and partial distal claviculectomy. Pathology of the resected specimen showed focally dense infiltration of plasma cells within the marrow space and scant hematopoiesis compatible with a plasma cell neoplasm. To the best of our knowledge, this is first case report of solitary plasmacytoma of bone, or any untreated plasma cell neoplasm, containing macroscopic fat upon imaging. The decision to forego image-guided percutaneous biopsy had significant treatment implications as the primary therapy for patients with SPB is not surgical, but localized radiation therapy. Based on this case, solitary plasmacytoma of bone may be included as one of the rare fat containing malignant bone lesions and imaging guided percutaneous biopsy should be considered in symptomatic fat-containing bone lesions.

Solitary plasmacytoma of maxillofacial bones: correlation of CT features with pathological findings

OBJECTIVE

To explore the CT features of solitary plasmacytoma (SP) of maxillofacial bones and correlation with pathological findings.

METHODS AND MATERIALS

We retrospectively reviewed the clinical, CT and pathological features of SP in the maxillofacial bones. 16 patients with clinically and histologically proven SP of maxillofacial bones were involved. They were aged from 27 to 79 years old (median 55.5 years old), and included 12 males and 4 females (males vs females: 3:1). All patients performed CT examination, in whom 13 patients underwent enhanced scanning and 3 plain scanning. The CT images were assessed for lesion location, size (maximum diameter), shape (round, oval and irregular), boundary (defined and illdefined), bone changes (bone destruction, residual bone, sclerotic margin and periosteal reaction), density of soft tissue mass and enhancement manifestations, and invasion of adjacent structures.

RESULTS

13 patients suffered from SP in the mandible, 2 in the zygoma, and 1 in the maxilla and hard palate. The maximum diameter of lesions ranged from 2.4 to 8.2 cm (mean 3.93 ± 1.435 cm). Most lesions were founded as a solitary osteolytic lesions (15/16, 93.75%) with round or ovoid shape (13/16, 81.25%), smooth margin (16/16, 100%) and defined boundary (16/16, 100%) in bone marrow. They destroyed bone cortex (15/16, 93.75%) and had residual bone (10/16, 62.5%), without sclerosis margin (15/16, 93.75%) and periosteal reaction (14/16, 87.5%). They easily formed soft tissue masses (16/16, 100%) and invade adjacent anatomical structures (15/16, 93.75%). The density of lesions was usually uniform (12/16, 75%) with strong enhancement. There was a significant difference in CT values between plain and enhanced scanning [50.75 ± 9.140 Hounfield unit (HU) vs 101.0 ± 28.830 HU; p < 0.001), with the mean difference of CT values 50.25 HU.

CONCLUSIONS

SP is predominant in the mandible of elderly male patients. A solitary, round or ovoid, well-defined, osteolytic, invasive mass in bone marrow, which destroys bone cortex, has residual bone, no sclerosis margin and periosteal reaction, and shows strong enhancement, is suggestive of this diagnosis.

Anaplastic plasmacytoma: a rare tumor presenting as a pathological fracture in a younger adult

Solitary plasmacytoma is the rarest type of plasma cell neoplasm, and the anaplastic form is even more uncommon. Plasmacytoma most commonly originates in bone and predominantly affects older patients. We describe the case of a 35-year-old woman with solitary osseous anaplastic plasmacytoma that presented initially with a pathological fracture following minor trauma. The patient was immunocompetent and had no predisposing conditions for a plasma cell tumor. Left lower extremity radiographs revealed an oblique fracture of the distal femur, and CT imaging indicated a primary osseous lesion at the fracture site. MRI confirmed the diagnosis of pathological fracture. Initial surgical pathology of the lesion was concerning because it could have been an osteosarcoma. Further immunostaining demonstrated CD138 positivity and kappa light chain restriction, confirming the diagnosis of plasmacytoma. In addition, the presence of marked anaplastic cellular changes confirmed the anaplastic variant. Further workup showed no evidence of multiple myeloma. This case is unusual given the age and gender of the patient. Awareness of the anaplastic variant of plasmacytoma is important to avoid erroneous diagnoses.

Chondrosarcoma of the para-acetabulum: correlation of imaging features with histopathological grade

OBJECTIVE

To evaluate the computed tomography (CT) and magnetic resonance (MR) imaging features of para-acetabular chondrosarcoma (CS) and assess the difference between low-grade CS (LGCS) and high-grade CS (HGCS).

MATERIALS AND METHODS

Thirty-one patients with histopathologically confirmed central para-acetabular CSs (6 LGCS and 25 HGCS) were retrospectively reviewed. Image features were evaluated for the following: cortical destruction, tumor border and pattern, calcification mode, soft-tissue mass, density/signal intensity, peritumoral edema, acetabular (cartilage) destruction, diffuse signal changes in acetabulum, mass inside hip joint, femoral head involvement, enhancement manifestations and the maximum length of the tumor. These image features between LGCS and HGCS were also assessed.

RESULTS

The most common CT and/or MR findings included cortical destruction, punctate, ring-and-arc and linear calcification, soft-tissue mass, lobulated border, high signal intensity with low signal septa on T2-weighted image, peritumoral edema, hip joint infiltration, peripheral and septal enhancement on post-enhanced MR image. Statistical analysis showed that the image features, such as cortical destruction, soft-tissue mass, hip joint infiltration and tumor size were significantly different between LGCS and HGCS (p < 0.05).

CONCLUSION

The characteristic radiological features of para-acetabular CSs are osteolytic lesions with cortical destruction, soft-tissue mass, lobulated border, calcification, and high signal intensity with low signal septa on T2-weighted MR image, peripheral and septal enhancement on post-enhanced MR image. Cortical destruction, soft-tissue mass, hip joint infiltration and tumor size can differentiate HGCS from LGCS.

Solitary Bone Plasmacytoma of the Pelvis: A Rare Tumor

Solitary bone plasmacytomas are part of a wide range of monoclonal neoplasms that share a common progenitor in the B lymphocyte lineage. In their particular case, a single bone lesion is found, most frequently on the axial skeleton, having evidence of no other osteolytic lesions or systemic involvement. Diagnosis can sometimes prove to be difficult as they are rare tumors, occurring in 3 to 5% (up to 10% in some series) of patients with plasma cell neoplasms, with important considerations regarding the differential diagnosis. We report a case of a solitary bone plasmacytoma, found on the ala of the left ilium of a patient during a routine consult due to hip pain.