Myxoid Variant of Solitary Fibrous Tumor: A Radiologic Chameleon.

SESSION TITLE: Cancer Case Report Posters IISESSION TYPE: Affiliate Case Report PosterPRESENTED ON: Tuesday, October 28, 2014 at 01:30 PM - 02:30 PMINTRODUCTION: Solitary fibrous tumors (SFT) of the pleura are rare. Most tumors are found incidentally on imaging performed for other reasons. We present the diagnosis of this rare tumor with a high index of clinical suspicion in a patient who presented with dysphonia and a right pleural effusion.

CASE PRESENTATION: A 69-year-old female presented for evaluation of dysphonia. She had no respiratory complaints and exercised actively. Her CXR revealed an elevated right hemi-diaphragm. (Image 1A) CT scan showed a large pleural effusion. Multiple thoracenteses yielded sero-sanginous, exudative fluid but no diagnosis from neither microbiological nor cytological analysis. Thoracoscopy with parietal pleural biopsy was performed and an indwelling tunneled pleural catheter inserted. Though grossly the pleura appeared normal, microscopic analysis showed SFT cells. After thoracentesis, a repeat CT scan showed a large inferior rounded defect with an attenuation coefficient consistent with fluid. (Image 1B) No discrete mass was identified. Based on the pathology result, thoracotomy was performed. No effusion was noted. Instead, a large mucin-filled tumor measuring (17 x 15 x 8.5 cm) was excised. (Image 2) The pathology was consistent with a myxoid variant of SFT with presence of CD34 immunoreactivity.DISCUSSION: We present this case to demonstrate an atypical presentation of a SFT. SFT are primary mesenchymal tumors that arise from the pleura and their imaging manifestations can vary.1 They may appear as a pleural mass, effusion or thickening. Classically, these tumors are well-defined, lobulated, exophytic and attached by a pedicle. Of interest, they can show mobility, changing shape and location on sequential images. The tumor will displace, rather than invade, surrounding tissue. On CT imaging they show variable enhancement following IV contrast administration. This patient was evaluated by non-contrast CT scan which showed a homogenous low attenuation mass considered a loculated large effusion within the right major fissure. Despite multiple non-contrast images over a span of time, no tumor was suspected radiologically. The homogenous appearance did not provoke a contrast study.

CONCLUSIONS: SFT remains an enigmatic tumor. Diagnosis may require a high index of suspicion and familiarity with the variable radiologic appearance of this radiologic chameleon! Reference #1: Cardinale et al. Imaging of benign solitary fibrous tumor of the pleura: a pictorial essay. Rare Tumors 2010 Mar; 2(1):e1.DISCLOSURE: The following authors have nothing to disclose: Faria Nasim, Jacobo Kirsch, Edward SavageNo Product/Research Disclosure Information.