Low-Grade Fibromyxoid Sarcoma and Hyalinizing Spindle Cell Tumor With Giant Rosettes

Abstract

Low-grade fibromyxoid sarcoma (LGFMS) is a rare sarcoma characterized by bland histologic features and a paradoxically aggressive clinical course. The hyalinizing spindle cell tumor with giant rosettes (HSCT) is a closely related tumor characterized by the presence of giant collagen rosettes. Only a single example of a metastasizing HSCT has been reported. A small subset of both LGFMS and HSCT display areas of increased cellularity and atypia which qualify as intermediate- to high-grade sarcoma; the significance of these features has not been definitively assessed. We present the clinicopathologic features of 77 cases of LGFMS and HSCT to determine the degree of overlap of these two lesions, their biologic behavior, and the significance of the occasional presence of intermediate- to high-grade sarcoma within both. The patients (33 female, 40 male) ranged from 3 to 78 years of age (median, 34 yrs). Fourteen cases occurred in patients less than 18 years of age. The tumors measured from 1 to 23 cm (median, 4.5 cm) and occurred predominantly in the trunk and lower extremities in both the deep (66 cases) and superficial (7 cases) soft tissues. In 15 cases, the tumor was present > 1 year before diagnosis. All tumors showed predominantly the typical hypocellularity and bland cytologic features of typical LGFMS; however, areas of hypercellularity and nuclear enlargement and hyperchromatism were identified in 12 of 73 (16%) and 7 of 73 (10%), respectively. Necrosis and mitotic activity >5/50 high-powered fields (HPF) were present in 6 of 73 (8%) and 5 of 73 (7%), respectively. Epithelioid areas were present in 33 of 73 (45%) and rosettes in 22 of 73 (30%). Follow up (54 cases; range, 2-192 mos; median, 24 mos; mean, 38 mos) showed 5 recurrences, 3 metastases, and 1 death. The diagnosis of LGFMS or HSCT was made prospectively in 51 patients; none had metastatic disease. Two of the metastatic tumors were LGFMS and one was a HSCT. LGFMS may occur more often in the pediatric population and show a much wider histologic spectrum than previously thought. A significant number of LGFMS possess inconspicuous collagen rosettes characteristic of HSCT, indicating that these two tumors are ends of a common spectrum rather than distinct entities. HSCT, like LGFMS, are low-grade sarcomas with metastatic potential. The presence of focal areas of intermediate- to high-grade sarcoma does not portend a worse outcome in the short term. The better prognosis reflected in this study compared with previous ones might reflect the fact that all were initially diagnosed as sarcomas and treated with aggressive surgery. The fact that the only three patients to develop metastatic disease were patients whose LGFMS or HSCT was identified retrospectively supports this concept.

Hyalinizing spindle cell tumor with giant rosettes

“…Cystic degeneration, which was prominent in our first case, is an uncommon finding 5. Our cases did not show areas with increased cellularity and nuclear atypia as is seen in the usual type of fibrosarcomas of intermediate grade 67…”

“…Both our cases showed these rosettes. The term HSCTGR has been used for those LGFMS where the collagen rosettes are particularly prominent and well-formed 1–3578…”

Low-Grade Fibromyxoid Sarcoma

“…[1][2][3][4][5][6] Histolojik olarak benign görünmesine rağmen agresif klinik gidiş gösterir. [1][2][3] Bu tümör genellikle genç erişkinlerde görülmekle birlikte ileri yaşlarda ve nadiren çocuklarda görülebilir. 2,6,7 LGFMS çoğunlukla derin yumuşak dokulara ; sıklıkla da kalça, inguinal bölge ve omuza lokalize olup büyük çapta olabilirler.…”

“…[1][2][3] Bu tümör genellikle genç erişkinlerde görülmekle birlikte ileri yaşlarda ve nadiren çocuklarda görülebilir. 2,6,7 LGFMS çoğunlukla derin yumuşak dokulara ; sıklıkla da kalça, inguinal bölge ve omuza lokalize olup büyük çapta olabilirler. 1,2,[6][7][8] Bu tümörler yavaş büyüme göstermelerine rağmen lokal rekürens ve metastaz yapabilirler.…”

“…2,6,7 LGFMS çoğunlukla derin yumuşak dokulara ; sıklıkla da kalça, inguinal bölge ve omuza lokalize olup büyük çapta olabilirler. 1,2,[6][7][8] Bu tümörler yavaş büyüme göstermelerine rağmen lokal rekürens ve metastaz yapabilirler. Metastazları sıklıkla akciğerde ve tanıdan uzun yıllar sonra ortaya çıkabilir.…”