INTRODUCTION: Benign mesenchymomas are soft tissue tumors that are composed of, in addition to fibrous tissue, multiple cellular elements not commonly associated together. Benign mesenchymomas are rare in adulthood and few cases have been reported. We report a case of benign, pleural-based mesenchymoma in an adult.
CASE PRESENTATION: A 41 year old, non-smoker, Asian woman was admitted to our hospital with a five month history of progressive dyspnea, cough, hemoptysis, right sided chest pain, and a twenty pounds weight loss. Physical examination was normal except for significantly diminished right sided air entry by chest auscultation, with associated dullness to percussion and decrease in tactile and vocal fremitus. Chest roentgenogram and computed tomography (CT) were performed and revealed a large hetereogeneous low density mass in the right hemithorax possibly originating from the pleura, causing a right-to-left mediastinal shift and partial right lung collapse. Subsequent fiber-optic bronchoscopy (FOB) demonstrated evidence of external compression of the basal segment of the right lower lobe of the lung; bronchial washing and brushing results yielded chronic bronchial inflammation without malignant cells. CT guided biopsy of the mass was performed but results were inconclusive. A right thoracotomy was performed and revealed a 2.2 kilogram, well encapsulated mass that measured 21 centimeters in its largest dimension and attached to the parietal pleura; no adjacent extension or invasion was visualized. After resection, repeat FOB showed resolution of the external compression of the basal segment of the right lower lobe without evidence of endobronchial lesions. Microscopic examination and immuno-histochemical staining revealed tumor positivity for anti-vimentin, anti-desmin, anti-smooth muscle, CD34, and negativity for CD99, BCL-2 and S-100. These results were consistent with benign mesenchymoma of the pleura, alternately termed myochondrolipoma.
DISCUSSIONS: Mesenchymomas are rare neoplasms that are malignant in approximately 75% of cases and most commonly present in childhood. First described by Stout, the tumor consists of, in addition to the fibrous tissue which is present in all mesenchymomas, two or more different cellular elements that are mesenchymal derivatives. While malignant tumors may cause distant metastases, benign tumors usually recur locally. Ionescu and Eskenasy reported a case of a benign thoracic mesenchymoma that recurred four times over the 30 years post initial resection. Prior case reports have noted tumor occurrence in various locations, including the urogenital tract, retroperitoneum, breast, liver, rectus femoris and gluteal muscles, lung, and mediastinum. A thorough literature review revealed only two prior reported cases of benign mesenchymoma of the pleura.
CONCLUSION: Smooth muscle, chondrocytes and adipose tissue were the three mesenchymal derivatives of our patient's tumor. The tumor was fully encapsulated and radically resected without microscopic evidence of malignancy. Thus, the patient is undergoing chest imaging every three months to ensure non-recurrence of the tumor. To date, she remains asymptomatic and imaging studies show no evidence of recurrence.
DISCLOSURE: Adel Blamoun, No Financial Disclosure Information; No Product/Research Disclosure Information