Diagnostic approach for mediastinal masses with radiopathological correlation.

PURPOSE: Mediastinal masses have various histopathological and radiological findings. Although lymphoma is the most common type of tumor, thymic epithelial and neurogenic tumors are common in adults and children, respectively, but several other types are difficult to distinguish. No previous review has simply and clearly shown how to differentiate mediastinal masses. METHOD: We conducted a review of the latest mediastinal classifications and mass differentiation methods, with a focus on neoplastic lesions. Both older and recent studies were searched, and imaging and histopathological findings of mediastinal masses were reviewed. Original simple-to-use differentiation flowcharts are presented. RESULTS: Assessing localizations and internal characteristics is very important for mediastinal mass differentiation. The mass location and affected organ/tissue should be accurately assessed first, followed by more qualitative diagnosis, and optimization of the treatment strategy. In 2014, the International Thymic Malignancy Interest Group presented a new mediastinal clinical classification. In this classification, mediastinal masses are categorized into three groups according to location: prevascular (anterior)-, visceral (middle)-, and paravertebral (posterior)-compartment masses. Then, the internal characteristics and functional images are evaluated. CONCLUSIONS: Differentiation of mediastinal masses is very difficult. However, if typical imaging findings and clinical characteristics are combined, reasonable differentiation is possible. In each patient, proper differential diagnosis may contribute to better treatment selection.

A case of inflammatory mass resulting from calcium crystal deposition disease around the thoracic spine.

Calcium crystal deposition diseases are transient benign diseases that can cause intense pain. They can sometimes cause masses and soft tissue edema around the calcification, which should be differentiated from tumors and abscesses. We report a case of calcium crystal deposition disease with an enhanced mass on the ventral side of the vertebral bodies resembling tumors and abscesses. A female patient in her 50s visited our hospital complaining of chest pain. Computed tomography revealed a soft tissue mass with polygonal high-density lesions on the ventral side of the thoracic spine. Initially, we suspected it to be a perivertebral tumor and considered a biopsy. However, the pain rapidly improved with the administration of oral acetaminophen (Caronal, Chuo-ku/Tokyo/Japan). Hence, the patient was followed up for the time being. The mass disappeared after 3 months. In addition, polygonal high-density lesions inside the mass disappeared over time. Therefore, it was diagnosed as an inflammatory mass due to calcium crystal deposition disease. Calcium crystal deposition diseases can cause soft tissue edema and inflammatory mass around the calcium crystal deposit that can be confused with a perivertebral tumor. This report elucidates the importance of identifying calcifications within and near the masses to diagnose an inflammatory mass resulting from calcium crystal deposition.