梭形细胞横纹肌肉瘤3例临床病理学分析及文献复习

目的探讨梭形细胞横纹肌肉瘤(spindle cell rhabdomyosarcoma,SCRM)的临床病理学特征、诊断及鉴别诊断。方法回顾性分析3例SCRM的临床表现、组织学与免疫表型特征,并复习相关文献。结果 3例均为男性婴幼儿,年龄2天~4岁。肿瘤部位:睾丸旁2例,腰背部1例,肿瘤直径2~6 cm;眼观:肿瘤边界清,无包膜,切面灰白色,质地韧。镜检:肿瘤呈侵袭性生长,边界尚清。瘤细胞由束状排列的梭形细胞组成,胞质深嗜伊红色,纤维状,可呈席纹状或漩涡状排列,局部区域可见波浪状结构,似神经纤维。部分细胞内可见横纹结构,有些区域见散在的横纹肌母细胞。瘤细胞间质内有少量胶原纤维。细胞核多为长圆形,有些细胞核呈纤细波浪状,细胞核异型不明显,核分裂象偶见。免疫表型:vimentin、desmin、myogenin和Myo D1均阳性,CK、α-inhabin、AFP、CD34、S-100蛋白均阴性。结论 SCRM是横纹肌肉瘤中一种少见的新类型,常发生于婴幼儿。需与婴儿纤维瘤病、先天性纤维肉瘤、纤维肉瘤、平滑肌肉瘤、恶性蝾螈瘤及促纤维组织的恶性黑色素瘤相鉴别。     

A case of primary spindle cell variant of embryonal rhabdomyosarcoma of the prostate

We treated a rare case of spindle cell variant of embryonal rhabdomyosarcoma (RMS) of the prostate of a patient referred to our hospital for gross hematuria. Computed tomography and magnetic resonance imaging revealed a 4-cm-diameter mass with focal cystic change. Transurethral resection (TUR) of the prostate was performed to diagnosis and treat for complete urinary retention. Microscopically, the TUR specimen almost comprised a fascicular proliferation of spindle-shaped tumor cells, leading to the diagnosis of spindle cell sarcoma. The consequent total prostatectomy revealed the presence of rhabdomyoblasts in addition to the spindle cell proliferation. A MyoD1 p.L122R mutation was not detected in this tumor. The tumor recurred locally, with multiple metastatic lesions found soon after surgery. The patient received chemotherapy and radiation therapy but died 10 months after initial presentation. Although MyoD1 mutation is reported to define a clinically aggressive subset of embryonal RMS, spindle cell variant of embryonal RMS shows extremely adverse clinical outcomes irrespective of MyoD1 mutation.     

Germline SDHB‐inactivating mutation in gastric spindle cell sarcoma

Gastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal tumors of the gastrointestinal tract. Inactivating mutations or epigenetic deregulation of succinate dehydrogenase complex (SDH) genes are considered defining features of a subset of GIST occurring in the stomach. Based on comprehensive molecular profiling and biochemical analysis within a precision oncology program, we identified hallmarks of SDH deficiency (germline SDHB‐inactivating mutation accompanied by somatic loss of heterozygosity, lack of SDHB expression, global DNA hypermethylation, and elevated succinate/fumarate ratio) in a 40‐year‐old woman with undifferentiated gastric spindle cell sarcoma that did not meet the diagnostic criteria for other mesenchymal tumors of the stomach, including GIST. These data reveal that the loss of SDH function can be involved in the pathogenesis of non‐GIST sarcoma of the gastrointestinal tract.     

成人梭形细胞横纹肌肉瘤9例临床病理学分析

目的探讨成人梭形细胞横纹肌肉瘤(spindle cell rhabdom yosarcoma,SRMS)的临床病理学特征、免疫表型和鉴别诊断。方法回顾性分析9例成人SRMS的临床资料、病理学形态和免疫组织化学标记结果。结果9例患者中7例男性,2例女性。年龄20～80岁,平均45岁。发生于头颈部4例,包括右下颌、咽部、鼻咽部和左上颌,占总数的44%。前臂、腰部、大腿、小腿、睾丸分别1例。均表现为逐渐增大的肿块。肿块直径2～14cm,平均5.9cm。组织学上主要由具有轻度非典型性的梭形细胞组成,呈交叉的束状排列,散在于梭形细胞之间有少量的梭形或多角形的横纹肌母细胞。在2例局灶区域可见明显的间质硬化,2例局灶区域可见假血管瘤样结构,1例散在少量疏松黏液样区域,在1例可见局灶区域瘤细胞呈轻度的多形性,但不见奇异核的横纹肌母细胞。免疫组织化学标记显示,梭形细胞表达vimentin、desmin、CD99和MyoD1,多数表达myogenin和MSA(分别为6例和7例),均不表达S-100、CD34、CK和HMB-45。术后随访6个月～4年,发生于睾丸患者有腹腔静脉旁转移,发生于小腿者有肝转移。4例复发,2例死亡。结论成人SRMS少见,好发于男性,头颈部是最好发部位,具有较强的侵袭性行为。形态学上应与多种梭形细胞肿瘤相鉴别。     

Pigmented spindle cell carcinoid tumour of the thymus with ectopic adrenocorticotropic hormone secretion: report of a rare variant and differential diagnosis of mediastinal spindle cell neoplasms

AIMS: A variety of histological variants of thymic carcinoid tumour have been described. A rare case of pigmented spindle cell carcinoid tumour of the thymus is documented and compared with the reported cases of thymic pigmented carcinoid tumour in the literature, with a discussion of the differential diagnosis of spindle cell tumours of the mediastinum. METHODS AND RESULTS: A thymic tumour with ectopic adrenocorticotropic hormone (ACTH) secretion was resected from a 24-year-old man suffering from Cushing's syndrome. Histological, immunohistochemical, and ultrastructural studies revealed an ACTH-producing spindle cell carcinoid tumour harbouring pigmented melanocytes. Among four thymic pigmented carcinoid tumours reported before, only one was similar to the present case by being also an ACTH-secreting pigmented spindle cell thymic carcinoid tumour. The clinicopathological features of this tumour distinguish it from a spindle cell thymoma, spindle cell thymic carcinoma, and other mediastinal spindle cell tumours. CONCLUSIONS: This case illustrates an extremely rare variant of thymic carcinoid tumour exhibiting a spindle cell morphology and harbouring pigmented melanocytes. Awareness of this histological variant is important in the differential diagnosis of spindle cell tumours of the mediastinum.     

Evaluation of new monoclonal anti-MyoD1 and anti-myogenin antibodies for the diagnosis of rhabdomyosarcoma

New monoclonal anti-MyoD1 and anti-myogenin antibodies were evaluated immunohistochemically to determine whether they are useful in discriminating rhabdomyosarcoma (RMS) from other soft tissue tumors in routinely processed sections. Neither MyoD1 nor myogenin was expressed in normal, mature striated muscle. In RMS, nuclear expression of MyoD1 and myogenin was found in 82 and 80% of non-overlapping cases, respectively. MyoD1 was generally expressed in small, primitive tumor cells, and larger cells exhibiting morphological evidence of skeletal muscle differentiation failed to express positive nuclear immunostaining. Positive nuclear staining for myogenin was stronger than that for MyoD1 in cases with abundant differentiated tumor cells, but was less prominent in cases in which small, primitive tumor cells predominated. No leiomyosarcomas, Ewing's sarcomas/peripheral primitive neuroectodermal tumors or other soft tissue tumors exhibited nuclear expression of MyoD1 or myogenin. In conclusion, both anti-MyoD1 and anti-myogenin antibodies are useful for diagnosing RMS and for discriminating RMS from other soft tissue tumors.     

Spindle cell rhabdomyosarcoma in the hypopharynx of an adult

We herein present the first-reported case in the English-language literature of a spindle cell rhabdomyosarcoma in the hypopharynx of an adult. A 58-year-old male presented with a progressive, 7-month history of discomfort during swallowing, accompanied by hoarseness for 1 month. Computed tomography and magnetic resonance imaging revealed a tumor in the left pyriform sinus; frozen section evaluation suggested that it was rhabdomyosarcoma. The tumor was removed completely via left lateral cervical incision. Section margins were negative, and laryngeal function was preserved. The postoperative pathological results indicated spindle cell rhabdomyosarcoma. The patient received postoperative radiotherapy (6,000 cGy in 200 cGy fractions, delivered over 30 days). However, he was also required to undergo urgent tracheostomy due to severe laryngeal obstruction, precipitated by laryngeal edema, 3 months subsequent to radiotherapy. The patient was free of disease 25 months postoperatively but is still unable to close his tracheostomy.     

Desmoplastic nested spindle cell tumours and nested stromal epithelial tumours of the liver

Desmoplastic nested spindle cell tumour of liver (DNSTL), nested stromal‐epithelial tumour (NSET) and calcifying nested stromal‐epithelial tumour (CNSET) are recently described entities with similar morphology, immunohistochemistry and molecular genetics. These are rare entities with only three large case series described till date. These tumours commonly present in the paediatric age group. NSETs, in addition have been described to be associated with ectopic adrenocorticotropic hormone (ACTH) production and Cushingoid features. It is important to discuss this rare group of tumours with a low malignant potential as the most common radiological differential diagnosis is hepatoblastoma, which has a relatively poorer prognosis. Thus, a pathologist needs to keep this entity in mind, so as to offer a correct histological diagnosis.     

Spindle‐cell rhabdomyosarcoma of the thumb: Rare site,rare tumor in a child

Spindle‐cell rhabdomyosarcoma (RMS) is a relatively recently recognized favorable variant of embryonal RMS occurring mainly in the paratesticular and head and neck regions. Cytological reports of spindle‐cell RMS have been sparse in the literature and the awareness of its cytological features is not very wide among cytopathologists. A 2‐year‐old girl was brought to clinical attention for a progressively enlarging swelling of right thumb. Imaging studies showed it to be a soft‐tissue tumor in the subcutaneous region. Fine‐needle aspiration yielded moderately cellular smears composed of small, round cells and few spindle cells with tapered cytoplasm. A cytological impression of RMS was rendered, which was later confirmed as spindle‐cell RMS on excision biopsy. Spindle‐cell RMS, a favorable prognostic variant of embryonal RMS, should be considered in the cytologic diagnosis of soft‐tissue tumors with round cell and spindle cell morphology. This is especially true for tumors occurring in hitherto unreported sites. Diagn. Cytopathol. 2016;44:1094–1097. © 2016 Wiley Periodicals, Inc.     

Next‐generation TCR sequencing – a tool to understand T‐cell infiltration in human cancers

Tumour‐infiltrating lymphocytes (TILs) are known to mediate potent anti‐tumour activity. As T‐cell‐based therapies start to reach clinical practice, it becomes increasingly important to understand what characterizes a successful anti‐tumour T‐cell response and to exploit this knowledge for patient stratification. Next‐generation sequencing of T‐cell receptors (TCRs) promises to provide insights into the complexity of the tumour T‐cell infiltrate that go beyond the phenotypic level. A recent study by Chen et al made use of this novel technology to demonstrate that the TIL repertoire of oesophageal squamous cell carcinoma patients is distinct from that of non‐tumour sites and is characterized by significant intratumoural heterogeneity. This study illustrates the great potential of the method and addresses several technical and biological hurdles that need to be considered. Careful sampling, normalization, and error correction will be required to optimally use TCR sequencing to answer biological questions and define predictive biomarkers, e.g. for cancer immunotherapy. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Missense variants in the X‐linked gene PRPS1 cause retinal degeneration in females

Retinal dystrophies are a heterogeneous group of disorders of visual function leading to partial or complete blindness. We report the genetic basis of an unusual retinal dystrophy in five families with affected females and no affected males. Heterozygous missense variants were identified in the X‐linked phosphoribosyl pyrophosphate synthetase 1 (PRPS1) gene: c.47C > T, p.(Ser16Phe); c.586C > T, p.(Arg196Trp); c.641G > C, p.(Arg214Pro); and c.640C > T, p.(Arg214Trp). Missense variants in PRPS1 are usually associated with disease in male patients, including Arts syndrome, Charcot–Marie–Tooth, and nonsyndromic sensorineural deafness. In our study families, affected females manifested a retinal dystrophy with interocular asymmetry. Three unrelated females from these families had hearing loss leading to a diagnosis of Usher syndrome. Other neurological manifestations were also observed in three individuals. Our data highlight the unexpected X‐linked inheritance of retinal degeneration in females caused by variants in PRPS1 and suggest that tissue‐specific skewed X‐inactivation or variable levels of pyrophosphate synthetase‐1 deficiency are the underlying mechanism(s). We speculate that the absence of affected males in the study families suggests that some variants may be male embryonic lethal when inherited in the hemizygous state. The unbiased nature of next‐generation sequencing enables all possible modes of inheritance to be considered for association of gene variants with novel phenotypic presentation.     

Enhanced Sensitivity for Detection of Low‐Level Germline Mosaic RB1 Mutations in Sporadic Retinoblastoma Cases Using Deep Semiconductor Sequencing

Sporadic retinoblastoma (RB) is caused by de novo mutations in the RB1 gene. Often, these mutations are present as mosaic mutations that cannot be detected by Sanger sequencing. Next‐generation deep sequencing allows unambiguous detection of the mosaic mutations in lymphocyte DNA. Deep sequencing of the RB1 gene on lymphocyte DNA from 20 bilateral and 70 unilateral RB cases was performed, where Sanger sequencing excluded the presence of mutations. The individual exons of the RB1 gene from each sample were amplified, pooled, ligated to barcoded adapters, and sequenced using semiconductor sequencing on an Ion Torrent Personal Genome Machine. Six low‐level mosaic mutations were identified in bilateral RB and four in unilateral RB cases. The incidence of low‐level mosaic mutation was estimated to be 30% and 6%, respectively, in sporadic bilateral and unilateral RB cases, previously classified as mutation negative. The frequency of point mutations detectable in lymphocyte DNA increased from 96% to 97% for bilateral RB and from 13% to 18% for unilateral RB. The use of deep sequencing technology increased the sensitivity of the detection of low‐level germline mosaic mutations in the RB1 gene. This finding has significant implications for improved clinical diagnosis, genetic counseling, surveillance, and management of RB.     

Genetic analysis of adult leukoencephalopathy patients using a custom‐designed gene panel

Leukoencephalopathies encompass all clinical syndromes that predominantly affect brain white matter. Genetic diagnosis informs clinical management of these patients, but a large part of the genetic contribution to adult leukoencephalopathy remains unresolved. To examine this genetic contribution, we analyzed genomic DNA from 60 Japanese patients with adult leukoencephalopathy of unknown cause by next generation sequencing using a custom‐designed gene panel. We selected 55 leukoencephalopathy‐related genes for the gene panel. We identified pathogenic mutations in 8 of the 60 adult leukoencephalopathy patients (13.3%): NOTCH3 mutations were detected in 5 patients, and EIF2B2, CSF1R, and POLR3A mutations were found independently in 1 patient each. These results indicate that cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) caused by NOTCH3 mutations is the most frequent adult leukoencephalopathy in our cohort. Moreover, brain imaging analysis indicates that CADASIL patients who do not present typical phenotypes may be underdiagnosed if not examined genetically.     

Transformation from EGFR/PTEN co‐mutated lung adenocarcinoma to small cell carcinoma in lymph node metastasis

There is minimal evidence of EGFR‐mutated lung adenocarcinoma transforming to small cell lung carcinoma (SCLC) without the administration of EGFR‐tyrosine kinase inhibitor (TKI). Here, we present a case of EGFR/PTEN co‐mutated lung adenocarcinoma with lymph node metastases, which comprised adenocarcinoma admixed with SCLC. EGFR L858R and PTEN R130Q mutations were shared between the primary tumor and lymph node metastasis. Additionally, EGFR I744M mutation was shared between the adenocarcinoma and SCLC components in the lymph node metastasis, confirming spontaneous transformation from adenocarcinoma to SCLC. Furthermore, TP53 and RB1 mutations were detected only in the SCLC components of the lymph node metastasis. Immunohistochemically, complete absence of Rb expression in SCLC was observed, suggesting the loss of function of RB1. Our case clearly shows that EGFR/PTEN co‐mutated lung adenocarcinoma transformed to SCLC in the lymph node without TKI‐mediated evolutionary selection pressures.