Contributed by Elia Guadagno1, Domenico Solari2, Gianpiero Iannuzzo2, Eduardo Clery1, Mariarosaria Cervasio1, Annarosaria De Chiara3, Marialaura Del Basso De Caro1
1Department of Advanced Biomedical Sciences, Pathology Section; 2Department of Neurosciences, Reproductive and Odontostomatological Sciences, Division of Neurosurgery University of Naples Federico II, Via Pansini 5, 80131 Naples- Italy; 3Pathology Unit, IRCCS National Institute of Tumors " G. Pascale Foundation", Naples, Italy
A 53-year-old woman presented with a growing mass in the left lumbar region. The patient had become casually aware of it ten years ago. Since then she performed radiological and clinical follow-up; she refused surgical resection. In 2009 a cytological examination had displayed mesenchymal cells without nuclear atypia. In the last year the tumor had been growing and had become symptomatic with pain during physical activity. Clinical examination revealed an unmovable swelling on the left lumbar region with intact skin. MRI showed a 9x4x5 cm T1 hypointense and T2 hyperintense mass, with a strong and heterogeneous enhancement after contrast infusion and a hypointense central core. It extended from the body of the second to the fifth lumbar vertebra. CT scan of the chest also revealed four pulmonary nodules enhancing with contrast, two of which were hypermetabolic during the whole body PET-CT scan (max SUV 2.7 and 2.4). The patient underwent surgical resection of the lumbar lesion which was easily removed with sharp dissection from the surrounding muscle fibers.
At gross examination the mass was encapsulated and its cut section was multinodular, glistening, mainly white and firm, with central areas of bone consistency (Fig. 1A). Histopathological examination of hematoxylin and eosin stain showed a partially circumscribed tumor, with biphasic appearance. The main aspect was a proliferation of atypical spindle cells arranged in fascicles, mitotically active (7 mitoses/10 HPF) and focally embedded in a myxoid matrix (Figs.1B, 1C); several foci of necrosis were detected. The second aspect was more differentiated and made of elongated bundles, interweaving fascicles and loose whorls of cells with wavy nuclei, without pleomorphism and in absence of mitoses (Figs. 1D, 1E). Bone metaplasia was present between these two areas. Immunohistochemical staining revealed diffuse reactivity to GLUT1 (Fig. 1F), CD10 (Fig.1G), EMA (Fig. 1H) and Bcl2 in the most differentiated area, but absence of reactivity in the most atypical areas. Both of them were focally reactive to CD34. Negative were S100 and CD99. Ultrastructural examination revealed the presence of spindle cells containing prominent pinocytic vesicles and surrounded by a focally discontinuous external lamina (Fig.1I). What is your diagnosis?