Metastatic melanoma mimicking solitary fibrous tumor: report of two cases

Malignant melanomas are known for their remarkable morphological variation and aberrant immunophenotype with loss of lineage-specific markers, especially in recurrences and metastases. Hot spot mutations in BRAF, NRAS, GNAQ, and GNA11 and mutations in KIT are oncogenic events in melanomas. Therefore, genotyping can be a useful ancillary diagnostic tool. We present one case each of recurrent and metastatic melanoma, both showing histological and immunohistochemical features of solitary fibrous tumor (SFT). Mutational analysis detected BRAF and NRAS mutations in the primary and secondary lesions, respectively. This result confirmed the diagnosis of recurrent/metastastic melanoma.     

Low-grade fibromyxoid sarcoma: analysis of 8 cases

The diagnosis of low-grade fibromyxoid sarcoma was made in 8 patients. The lesions were 2-17 cm in the lower extremities and trunk. One patient had a long history of painless subcutaneous and intramuscular mass (median 1 year). All tumors showed predominantly the typical hypocellularity and cytologic features of typical low-grade fibromyxoid sarcoma; however, the areas of hypercellularity and nuclear enlargement and hyperchromatism were identified. No necrosis and mitotic activity less than 2 mf/50 HPF were present. Ultrastructurally, the tumor composed of neoplastic fibroblasts. No other cell differentiation was identified. Immunohistochemically, the neoplastic cells showed a positive response to vimentin and fibroblast antigen; no muscle-specific antigens were revealed. The Ki-67 labeling index with MIB-1 ranged 2-6%.     

低度恶性纤维黏液样肉瘤的病理学观察

目的 探讨低度恶性纤维黏液样肉瘤(LGFMS)的临床病理学特征、免疫学表型和鉴别诊断.方法 分析9例LGFMS的临床表现、影像学、组织学和免疫学表型特点.免疫组织化学染色采用EnVision法,所用一抗为波形蛋白、平滑肌肌动抗原(α-SMA)、肌特异性抗原(MSA)、高分子钙调蛋白(h-caldesmon)、结蛋白、CD34、CD99、S-100蛋白、CD57(Leu 7)、bcl-2、细胞角蛋白(AE1/AE3)、上皮细胞膜抗原(EMA)和KP-1(CD68).结果 男性5例,女性4例,年龄范围为11-65岁(平均31.4岁).临床上表现为四肢、躯干和颈部缓慢增大的无痛性肿块,2例有近期内肿块生长迅速的病史,3例因肿块局部切除后复发就诊.超声检查显示肿瘤内信号高低不一.CT平扫显示为低至等密度的结节状肿块,增强CT提示肿瘤内密度不均.MRI-T1加权显示为低密度信号,MRI-T2加权显示高密度和低密度区域交错性分布.大体上肿块呈结节状,直径为3～16 cm(平均7.7 cm),切面呈灰白色,纤维至纤维黏液样.组织学上,肿瘤由交替性分布的胶原性区域和黏液样区域组成,两种区域之间可见有移行.3例肿瘤内另见有巨菊形团形成.在巨菊形团与纤维黏液性成分之间也有过渡现象.巨菊形团的中央由嗜伊红色的胶原纤维组成,常呈离心状排列.高倍镜下,瘤细胞呈短梭形或卵圆形,核深染,异型性不明显或仅有轻度的异型性,核分裂象罕见.瘤细胞多呈交织状或旋涡状排列.肿瘤内血管不丰富,也不见凝固性坏死.免疫组织化学标记显示瘤细胞主要表达波形蛋白,部分表达CD34,不表达α-SMA、结蛋白、h-caldesmon、CD99、S-100蛋白和bcl-2等标记.结论 LGFMS是一种好发于青年人的低度恶性纤维母细胞性肉瘤,熟悉其临床病理学特征有助于避免将其误诊为良性肿瘤.临床上对LGFMS宜采取局部扩大切除术,以降低局部复发的危险性.     

Low-grade fibromyxoid sarcoma

A low-grade fibromyxoid sarcoma arising in the thigh of a 16-year-old Japanese girl is described. The patient had a well-circumscribed mass measuring 3.5 cm in its greatest diameter within her left vastus medialis muscle and a 6-month history of pain. Microscopically, the tumour was not encapsulated and filtrated into adjacent skeletal muscle. The tumour was characterized by poor to moderate cellularity, a proliferation of bland-appearing spindle tumour cells, and alternating fibrous and myxoid areas with a whorled pattern of the tumour cells. Neither cellular atypia nor mitotic figures were observed. There was no tumour necrosis. Immunohistochemically, the tumour cells were diffusely and strongly positive for vimentin and desmin. Some cells contained alpha smooth muscle actin. They were uniformly negative for CAM5.2, epithelial membrane antigen, muscle-specific actin (HHF35), factor-VIII-related antigen, S-100 protein, neurofilament, CD34, and CD31. The tumour had a diploid DNA content with S-phase fractions of 6.6% by flow cytometry. The patient was alive with no evidence of disease 11 months after excision.     

Low-grade fibromyxoid sarcoma: a brief review

Low-grade fibromyxoid sarcomas are uncommon deep soft tissue neoplasms first described by Evans in 1987. They exhibit a deceptively benign appearance, with a whorled or linear arrangement of spindle-shaped cells showing few to absent mitoses. A characteristic, but not specific, feature is the presence of areas of myxoid stroma. Recurrences are common, and late metastases have been recorded. A closely related but morphologically distinct tumor, the so-called hyalinizing spindle cell tumor with giant rosettes, has also been described; both neoplasms share the same cytogenetic abnormality, a balanced translocation resulting in a FUS/CREB3L2 fusion gene. Because of similar clinical behavior and the common cytogenetic abnormality, some authors prefer to consider both lesions as a single entity within the spectrum of low-grade sarcomas.     

Low-grade fibromyxoid sarcoma. A report of two metastasizing neoplasms having a deceptively benign appearance

Two deceptively benign-appearing, unclassifiable but very similar fibromyxoid sarcomas characterized histologically by bland, innocuous-appearing fibroblastic cells and a swirling, whorled growth pattern are presented. The tumors both occurred in women in their late twenties and were located in the soft tissues of the scapular area and the axillary-chest wall area, respectively. Lung metastases developed in both cases; one patient died 94 months after excision of the primary neoplasm, whereas the other was alive at 82 months. The designation "low-grade fibromyxoid sarcoma" is suggested for these tumors.     

Extrapleural solitary fibrous tumor mimicking lateral neck cyst--a case report

A 62-year-old man was referred to the Department of Dentistry because of ultrasonographic finding of "cystoid lesion with relationship to right parotid gland". During operation, a tumor mass without any relationship to parotid gland but attached to the right internal carotid artery was found. Grossly, the tumor was well circumscribed, spheric, measuring 40 mm in diameter; it was of solid, firm appearance and tan-to-white color on cross section. Microscopically, the tumor cells were round to spindle-shaped with vesicular nuclei and eosinophilic cytoplasm, arranged in fascicular pattern. Immunohistochemically, the cells expressed vimentin, CD 34, smooth muscle actin, and bcl-2 protein. On the basis of microscopical appearance and results of immunohistochemistry, the diagnosis of solitary fibrous tumor (cellular variant) was established. One year after resection, the patient is free of disease. A new concept of this uncommon mesenchymal tumor is discussed.     

Low-grade fibromyxoid sarcoma: a report of eight cases with histologic, immunohistochemical, and ultrastructural study

We present eight cases of low-grade fibromyxoid sarcoma (LGFS) of soft tissues. The patients, six men and two women, ranged in age from 28 to 44 years (median, 39 years). All tumors were subcutaneous. They were located in the lower extremity (three cases), inguinal/perineal region (two cases), trunk (one case), upper extremity (one case), and neck (one case). Grossly, the lesions were similar to those described in previous studies; fibrous and well circumscribed, with pseudocapsules, and without any necrosis or nodularity. In a single case of hemosiderin-rich tumor, rusty brown strips were seen on the cut surface. Histologically, the tumors were composed of alternating fibrous and myxoid areas with various cellularity and with swirling and whorled growth patterns. The cells were stellate or spindle shaped and displayed none to mild nuclear pleomorphism and hyperchromasia. Some hypercellular areas showed a fascicular or herring bone pattern similar to common fibrosarcomas. In addition to the known typical picture of LGFS, we also have seen some unusual features. The cells of myxoid areas were often arranged in rows, thus resembling ossifying fibromyxoid tumor or myxoid chondrosarcoma of soft tissues. In a single case, the tumor cells contained a large amount of hemosiderin and the cellular nests contained synovial metaplasia-like clefts. The intranuclear invaginations of cytoplasm represented another interesting finding that was present in all tumors in our series. They seem to be constant or at least frequent features of LGFS, which may assist in the differential diagnosis. The immunohistochemical and ultrastructural findings were consistent with the fibroblastic nature of LGFS. Four cases also showed features of possible histiocytic modulation of the neoplastic fibroblasts.     

Low-grade fibromyxoid sarcoma: an unusual cardiac location

We report the unusual cardiac localization of a primary low-grade fibromyxoid sarcoma of the right ventricle in a 57-year-old woman. Histological examination revealed a prevalent myxoid appearance with whorling growth pattern of small or spindle cells with bland features alternating with rare more collagenous hypocellular areas with rare atypical cells. Genomic polymerase chain reaction of genomic DNA revealed the typical FUS/Creb3L2 fusion gene products typical of low-grade fibromyxoid sarcoma. The tumor was surgically removed and recurred after 7 years as high-grade pleomorphic sarcoma. The patient died 6 months after the clinical manifestation of recurrence. Low-grade fibromyxoid sarcoma of soft tissues is a rare, distinctive variant of fibrosarcoma—typically arising in deep soft tissue of lower extremities and trunk—that rarely metastasizes. Clinically, low-grade fibromyxoid sarcoma is characterized by a longer survival rate compared to other sarcomas, suggesting its consideration in the differential diagnosis of cardiac tumors with a myxoid appearance.     

盆腔囊性孤立性纤维瘤一例

患者女,47岁.因发现下腹部肿块2年于2007年9月19日收入院.体检:患者一般情况良好,妇科检查发现宫体增大如孕50 d大小,左附件区触及15 cm×10 cm×10 cm包块.盆腔彩超提示:左附件区多房囊性占位(考虑卵巢囊腺瘤);子宫多发性平滑肌瘤.     

Biphasic solitary fibrous tumour: a report of two cases with epithelioid features

We present two cases of solitary fibrous tumour (SFT) showing biphasic morphology with a spectrum of malignant epithelioid components. Slides prepared from formalin-fixed and paraffin-embedded tissue from both cases were stained with haematoxylin and eosin and by immunohistochemistry. Interphase fluorescent in situ hybridisation studies were performed in both cases using paraffin-embedded tissue to look for the t(X;18) translocation, thereby to exclude synovial sarcoma. Both cases showed biphasic morphology with some areas having typical benign spindled SFT morphology (including CD34 expression) and other areas having a malignant epithelioid appearance. In one of the cases, the epithelioid area, which was well circumscribed and showed packeting of cell groups, demonstrated expression of cytokeratin and epithelial cadherin but not of CD34. In the second case, the immunophenotype of the epithelioid component was similar to that of the benign SFT component. These findings suggest that epithelioid change in SFT shows a range of differentiation at one end, similar to that of a standard SFT, and at the other end, possibly acquiring epithelial characteristics.     

胸膜外孤立性纤维性肿瘤

例1男,68岁。进行性排尿困难4个月余,于2004年12月12日入院。入院检查会阴部可触及分叶状肿块12 cm×10 cm×5 cm,质硬且固定;术中发现肿块来源于前列腺。病理检查:分叶、结节状组织11．5 cm×10．0 cm×4．0 cm,部分似有包膜,部分已切开,切面鱼肉状,质嫩。显微镜下肿瘤境界清,有较厚的纤维性包膜,肿瘤由富细胞区和细胞稀疏区组成。富细胞区肿瘤细胞呈束状或成簇状的小圆形、卵圆形细胞,部分区杂乱无章(图1)。瘤细胞胞质少,核染色质均匀,核仁不明显,无核分裂象,部分区肿瘤血管丰富;细胞稀疏区含多量胶原纤维。免疫组织化学示:波形蛋白、CD34、Bcl-2均(+,图2,3),CD99(±),肌动蛋白、S- 100、神经微丝(NF)、结蛋白、平滑肌肌动蛋白(SMA)、细胞角蛋白(CK)、CD117均(-)。病理诊断:胸膜外孤立性纤维性肿瘤。     

Low-grade fibromyxoid sarcoma metastatic to the prostate

Spindle cell tumors of the prostate are rare and mostly primary. We report a case of retroperitoneal sarcoma, which is a low-grade fibromyxoid sarcoma involving the prostate secondarily by metastasis. The patient was a 44-year-old man who presented with progressing abdominal pain. Computed tomography showed a large retroperitoneal mass. The patient underwent surgical resection. Intraoperatively, a second smaller mass was identified in the pelvis and was left untouched. The resected retroperitoneal specimen and prostate transrectal needle biopsies taken afterward showed the same mesenchymal tumor. Radical cystoprostatectomy was performed. Metatatic tumor involving the prostate, bilateral seminal vesicles, and base of the urinary bladder was found. Microscopic examination revealed typical histomorphologic features of low-grade fibromyxoid sarcoma. The patient is without evidence of disease 3 years postoperatively. This case is the first documentation of metastatic sarcoma to the prostate and expands the list of malignant mesenchymal neoplasms that may involve this organ.     

Solitary fibrous tumor of the prostate: a report of two cases

We here report two cases of solitary fibrous tumor (SFT) arising in the prostate. Two men, 66 and 69 years old, with urinary tract symptoms were diagnosed with SFT on transrectal needle biopsy and transurethral resection of the prostate, respectively. The tumors were removed by a low anterior resection including tumor, prostate and rectum en bloc and cystoprostatectomy, respectively. Both tumors were well-circumscribed but also showed some infiltration of the prostate glands. They were composed of storiform bundles of bland spindle cells that stained strongly for CD34 and vimentin but negative for muscle markers. Although rare, SFT should be considered as differential diagnosis of spindle cell lesions on prostate biopsies.     

Hepatic solitary fibrous tumor: report of a rare case

Solitary fibrous tumor (SFT) of the liver is an extremely rare neoplasm of mesenchymal origin. In the English literature, less than 40 cases of SFTs of the liver have been reported. The present case concerns a 34-year-old female who presented to us with complaint of dyspepsia. On examination, there was hepatomegaly. On ultrasound examination, an SOL in the liver was detected. Large tumor measuring 14.5 × 10 × 8 cm was resected. Microscopic evaluation of the tumor showed a well-circumscribed, low to moderately cellular tumor demonstrating spindle- and fibroblast-like cells within the collagenous stroma. Immunohistochemistry revealed diffuse strong cytoplasmic immunopositivity of CD34, Bcl2, and vimentin. A diagnosis of a benign SFT was given. The patient remained well 4 years after surgery. SFT is a rare mesenchymal neoplasm that occasionally involves the liver in adult patients. Most SFTs are benign, but some may have malignant histological features. With less than 40 reported cases in the literature, little can be said regarding its natural history or the benefits of adjuvant radio chemotherapy. Complete surgical resection remains the cornerstone of its treatment.     

Low-grade fibromyxoid sarcoma arising in the big toe

Low-grade fibromyxoid sarcoma (LGFMS) is a rare tumor. Reported herein is a case of LGFMS arising in the big toe. The patient was a 58-year-old man who underwent excision of the tumor. The tumor was well-demarcated. Histologically, there were proliferating spindle-shaped tumor cells arranged in a whorled growth pattern, and the stroma showed hyalinized collagen bundles and a myxoid matrix. Nuclear mitotic figures were conspicuous in part. A large rosette-like structure with hyalinized stroma was found, which is characteristic of LGFMS. The differential diagnosis included tumor occurrence in adults; tending to arise in distal extremities; and having bland fibromyxoid histological features, such as fibroma of tendon sheath, low-grade myxofibrosarcoma and acral myxoinflammatory fibroblastic sarcoma. It was not possible to detect the FUS/CREB3L2 and FUS/CREB3L1 fusion genes from the formalin-fixed and paraffin-embedded tissue, although the histological features of the present case were typical of LGFMS. LGFMS may become more common with time, and unique cases may accumulate.     

恶性孤立性纤维性肿瘤4例临床病理分析

目的探讨恶性孤立性纤维性肿瘤(malignant solitary fibroustumor,MSFT)的临床病理特征、组织发生、诊断、鉴别诊断、治疗及预后。方法报道4例罕见的MSFT,并结合文献进行复习。结果女性2例,男性2例,年龄22岁～63岁,中位年龄42.5岁。发生部位:中枢神经系统2例,临床表现为头痛、头晕和恶心等;胸腔2例,无明显症状,体检发现。肿块直径3～14cm,平均8.5cm。镜检:低倍镜下肿瘤细胞分布疏密不均。密集区肿瘤细胞丰富,呈束状、漩涡状或不规则状排列,可见血管外皮瘤样结构;瘤细胞梭形、短梭形,核染色质粗且不均匀,异型性明显,核分裂象多见(4个/10HPF),局灶出血坏死。疏松区细胞稀少,纤维化伴黏液变性。免疫表型:肿瘤细胞Bcl-2、CD99、vimentin弥漫阳性;CD34、MSA、α-SMA、h-caldesmon局灶阳性,Ki-67增殖指数25%～50%;EMA、CD117、GFAP和S-100阴性。结论 MSFT非常罕见,确诊主要依赖病理形态学和免疫表型,需与滑膜肉瘤、脑膜瘤、恶性外周神经鞘膜瘤、恶性纤维组织细胞瘤和纤维肉瘤等相鉴别。MSFT的预后不佳,易复发和转移,手术完整切除后,应注意随访。