Imaging Findings With Histopathologic Correlation Of Solitary Plasmacytoma

ObjectiveThis study consists of two parts. The first part summarizes the imaging characteristics of solitary plasmacytoma (SP), the second part correlates the imaging findings to the pathologic grade, aim to improve the understanding of SP.Part1Imaging features of solitary plasmacytomaMethodsA retrospective study was performed on the imaging features of37patients with a histological diagnosis of SP, with solitary plasmacytoma pf bone (SPB)31cases, extramedullary solitary plasmacytoma (EMP)6cases. The imaging studies of SPB were assessed for the tumor location, bone expansion, remainning bone, cortical destruction, Periosteal reaction, representation and enhancement manifestations of soft tissue mass. Divide SPB into A, B, C three groups according to the site, representing the spine, long bone and flat bone, comparison and analysis of its imaging features. The imaging studies of EMP were assessed for the tumor location, enhancement manifestations of soft tissue mass and bone destruction.ResultsOf31cases of SPB,11cases occured in spine (group A),14cases in flat bone (group B) and6cases in long bone (group C). All the cases are osteolytic lesion without periosteal reaction, while slight expansion was seen in27cases, marked expansion in4cases; remainning bone in29cases, complete bone destruction in2cases; soft tissue mass within the bone destruction region in16cases, outside the region in15cases. The soft tissue mass were homogeneous density on CT scans; low signal intensity on T1WI in17cases, high signal on T1WI in one cases; high signal on T2WI in all cases and homogeneous enhancement in19cases, hetergeneous enhancement in2cases on enhanced CT/MR, with all marked expansile lesion, complete bone destruction and hetergeneous enhancement in Group B. Of6cases of EMP,2cases occured in the nasal cavity and brain respectively, one case in spleen and oropharynx respectively. CT scan showed homogeneous density in3cases, hetergeneous density in one cases. MR plain scan were isodense on both T1WI and T2WI, and homogeneous enhancement after contrast.Part2Pelvic Solitary Plasmacytoma:Imaging Findings with Histopathologic CorrelationMethodsA retrospective study was performed on the imaging features of10patients with a histological diagnosis of pelvic SP. The imaging studies were assessed for bone expansion, cortical destruction, signal/density of soft tissue mass and enhancement manifestations and were then correlated to the pathologic grade. ResultsThe imaging features of pelvic SP revealed the three different type:multilocular type (n=4), unilocular type (n=3) and complete osteolytic destruction type (n=3) on CT and MRI. Pathologically, the tumors were classified into low, intermediate and high grade. Features such as multilocular change, perilesional osteosclerosis, slight expansion, local bone cortex disruptions and masses inside bone destruction, often suggest a low grade SP; complete osteolytic destruction, huge soft tissue mass, and osseous defects imply a higher pathologic grade.Conclusions1. SPB has certain imaging manifestations, a slight expansile osteolytic lesion, especially a lesion with multilocular change or a mass with homogeneous enhancement highly suggests the diagnosis.2. That distinctive image appearance of SPB is closely correlated to its pathologic grade. CT and MRI findings may be helpful to its pathologic classification.3. Imaging findings of EMP are not specific, generally present as an uniform density/signal soft tissue mass, with well-defined boundary, enhanced CT/MR shows moderate-marked enhancement, the adjacent bones can be violated.4. CT and MR examination complement each other, CT is easy to observe the bone destruction of lesions, while MRI is better at showing the enhancement features of soft tissue mass.