Ectopic hamartomatous thymoma in an immunocompromised male

Ectopic hamartomatous thymoma (EHT) is a rare benign neoplasm classically occurring in the lower neck of adult males. Here we present a case of EHT occurring in a 43-year-old immunocompromised male and a brief review of existing literature. The patient presented with a palpable mass overlying the left clavicle which, on imaging, showed a solitary nodule possibly eroding the cortical bone. A biopsy predominantly showed spindle cells that were immunopositive for keratin AE1/AE3 as well as weakly positive for CD99, SMA, and CD34. A diagnosis of synovial sarcoma was favored; at which point surgical resection was performed. The resected mass was well-demarcated with a tan-yellow cut surface. Microscopically, the lesion was composed of a mixture of spindle cells, glands, and mature adipose tissue. The spindle cells were plump with bland nuclei, and the epithelial component showed morphology similar to glands of salivary or breast tissue with a bilayered appearance (luminal and basal). No pleomorphism, mitotic figures, or necrosis was present. Immunohistochemical stains were performed and showed the spindle cells to express a myoepithelial phenotype (cytokeratin AE1/AE3, p63, calponin positive). The glands showed SMA and p63 positivity in the basal cells (similar to salivary gland and breast). Overall, given the clinical context, histomorphologic, and immunohistochemical profile, a diagnosis of EHT was made. At 12 months of follow-up there was no evidence of recurrence.     

异位错构瘤性胸腺瘤的临床病理学观察和免疫组织化学研究

目的探讨异位错构瘤性胸腺瘤的临床病理学特征、免疫学表型和组织发生。方法对2例异位错构瘤性胸腺瘤进行临床病理学分析,采用免疫组织化学LSAB法行AE1/AE3、细胞角蛋白(CK)5、CK7、CK8、CK20、上皮膜抗原(EMA)、波形蛋白、CD5、CD10、α-平滑肌肌动蛋白(SMA)、calponin、结蛋白、CD34、S-100蛋白、CD57、胶质纤维酸性蛋白(GFAP)、甲状腺转录因子(TTF)-1和CD99标记。结果两例均发生于男性,年龄分别为20岁和40岁,因发现胸骨柄上缘肿块6个月和左锁骨上肿块2个多月就诊。肿块呈球形和卵圆形,边界清楚,最大直径分别为5cm和3cm,切面呈灰白色,质地柔软。组织学上,肿瘤由梭形细胞、上皮细胞和成熟的脂肪细胞3种成分混合组成。梭形细胞成分在2例中分别占到85%和70%,形态上类似纤维母细胞,多呈束状、编织状或席纹状排列。上皮细胞成分在两例中均占10%左右,形态上以非角化性鳞状上皮为主,可呈实性的小岛屿状、类似造釉细胞瘤的条索状和扩张的囊肿样排列,部分区域显示腺样分化,可见腺管形成。上皮细胞和梭形细胞在形态上有移行。成熟的脂肪组织呈不规则性分布,在两例肿瘤中所占的比例分别为<5%和20%。免疫组织化学标记显示,上皮细胞表达AE1/AE3、CK5、CK7、CK8和EMA,梭形细胞除CK外还表达波形蛋白、CD10和CD34,并部分表达α-SMA和calponin。两种细胞成分均不表达CK20、CD5、TTF-1、结蛋白、S-100蛋白、CD57、GFAP和CD99。结论异位错构瘤性胸腺瘤是一种好发于中青年男性锁骨上和胸锁关节附近软组织内的良性肿瘤,是一种由上皮和肌上皮组成的混合性肿瘤,可能起自于His颈窦,采用鳃原基混合瘤来命名或许更为合适。     

Ectopic hamartomatous thymoma: a case report with immunohistochemical and ultrastructural studies

A case of ectopic hamartomatous thymoma (EHT) arising in the supraclavicular region of a 52-year-old male is presented. The well-defined tumor measuring 1.7x1.5x0.7 cm consisted of three components: spindle cell (70%), epithelial (25%), and adipose (5%). The spindle cell component was characterized by sheet-like, haphazard and short fascicular arrangements of bland spindle cells. Neither mitotic figures nor cellular pleomorphism were found. Admixed with, and adjacent to, the spindle cell areas was an obviously epithelial component of variable appearance, ranging from glandular spaces lined by mainly cuboidal clear cells, irregularly anastomosing cords, and strands of epithelial cells to irregular solid nests of squamous epithelium with dark and clear cytoplasm. Myoepithelial cells were also observed. Immunohistochemically, the spindle cells were strongly and diffusely positive for cytokeratins and some of them were positive for BRST2, alpha-smooth muscle actin, and CD10. The tumor was negative for S-100 protein, glial fibrillary acidic protein, and CD34. Ultrastructurally, tonofilaments and desmosomes were observed in the spindle cells. The findings indicate an epithelial origin. The patient was well without recurrence or metastasis 8 months after excision. Pathologists and clinicians should be aware of the existence of ectopic hamartomatous thymoma in the supraclavicular or suprasternal region and should differentiate it from a high-grade sarcoma, such as biphasic synovial sarcoma or glandular malignant peripheral nerve sheath tumor.     

异位性错构瘤性胸腺瘤1例报道及文献复习

目的 探讨良性异位性错构瘤性胸腺瘤的临床病理特征及其鉴别诊断.方法 石蜡包埋组织连续切片分别做HE染色和免疫组化染色,光镜观察,分析1例异位性错构瘤性胸腺瘤的临床病理学特征及免疫表型特征,并进行文献复习.结果 肿块位于左颈部,生长缓慢.大体为结节状,包膜完整,切而部分囊性变.镜下显示肿瘤由梭形细胞、上皮样细胞、脂肪细胞和少量淋巴细胞组成.免疫组化染色显示:梭形细胞和上皮样细胞均弥漫性强阳性表达细胞角蛋白CK7、CK8、CK、CK5/6,不表达desmin、TTF-1、GFAP,,此外,梭形细胞阳性表达p63、Calponin、SMA、CD10、CD34,不表达细胞膜抗原EMA.而与之相反的是上皮样细胞阳性表达EMA不表达SMA、CD10、CD34.结论 异位性错构瘤性胸腺瘤是一种罕见的良性肿瘤,好发于中青年男性的颈部下方、锁骨上方及胸骨上方,需要与其它双向分化的肿瘤尤其是高级别肉瘤如滑膜肉瘤或腺样恶性外周神经鞘膜瘤鉴别,故该肿瘤的诊断及鉴别诊断尤为重要.     

Cytokeratin profiles of the thymus and thymomas: histogenetic correlations and proposal for a histological classification of thymomas

AIMS: Since cytokeratins (CKs) are useful as differentiation markers for histogenetic and classification studies, we investigated the CK profiles of the thymus and thymomas in an attempt to understand the histogenetic correlation and to propose a histological classification. METHODS AND RESULTS: Nine thymuses and 34 thymomas were immunostained for various CKs of different molecular weights and involucrin. Based on cytomorphology and histoarchitecture, thymomas were classified into spindle cell (SC), small polygonal cell (SPC), mixed, organoid, large polygonal cell (LPC) and squamoid (SQ) thymomas for compiling CK profiles. The thymus was shown to comprise four epithelial compartments, each expressing a different CK profile. Different histological types of thymoma expressed different CK profiles. By correlating the CK profiles of the thymus and thymoma, SPC, SC and LPC thymomas appeared to be related to subcapsular, medullary and cortical cells, respectively. Organoid thymoma recapitulated the structure and CK profile of the normal thymus, while SQ thymoma acquired additional squamous type CK. The applicability and usefulness of the proposed histological classification were evaluated on 147 thymomas by correlating the results with their invasive behaviour. One hundred and thirty-nine cases (95%) could be classified and different histological types correlated strongly with their invasive behaviour. CONCLUSIONS: The thymus is a complex epithelial organ composed of heterogeneous cell types giving rise to various related histological types of thymoma. The results of the CK profile study supports the proposed histological classification, which is pathologically applicable and clinically useful in correlating with invasiveness. This cytomorphological classification, supported by the CK expression patterns, is comparable to Müller-Hermelink classification and the new WHO histological classification except that a separate group of SPC thymoma expressing only CK14 and CK19 was identified and separated from mixed thymoma.     

Two cases of ectopic hamartomatous thymoma

Ectopic hamartomatous thymoma (EHT) is a rare benign neoplasm. Since it was named by Rosai et al. in 1984, 24 cases have been reported. We herein report two cases of EHT, one of which presented with massive myoid cells, and review the literature related to EHT. Both of our cases displayed the typical features of EHT: (1) nests of epithelial cells, including solid, cystic, or glandular epithelial islands; (2) spindle cells dominating the microscopic picture; and (3) adipose cells which intermingle haphazardly to impart a hamartomatous quality to the tumor. In this paper, we observed massive myoid cells and the transition from spindle epithelial cell to myoid cell in one of our cases. Immunohistochemical examinations showed that the main component of EHT, spindle cells, was positive for cytokeratin and epithelial membrane antigen (EMA). Intriguingly, the myoid cells simultaneously expressed cytokeratin, EMA, myoglobin, and creatine kinase-mm, suggesting that myoid cells may originate from epithelial cells and are an intermediate state between epithelial cells and muscular cells.     

微结节性胸腺瘤伴淋巴样间质3例临床病理观察

目的:探讨微结节性胸腺瘤伴淋巴样间质(micronodular thymoma with lymphoid stroma,MNT)的临床病理特征.方法:通过组织学和免疫组织化学方法观察3例MNT,研究其临床病理特征,并复习文献.结果:肿瘤有纤维性假包膜,肿块内见多发性散在或局部融合的上皮性结节,由丰富淋巴细胞间质分隔,其中可见淋巴滤泡形成.上皮性结节由温和的细长形或卵圆形细胞组成,核仁不明显,结节内淋巴细胞稀少.免疫组织化学:上皮性结节内上皮细胞CKpan,CK5/6,CK19,CK8/18均阳性,Ki67约2%阳性,CD20,EMA阴性;间隔内淋巴细胞CD20,CD3,CD5,CD99,TdT均灶区阳性,p53,CD1α均散在阳性;淋巴细胞背景内CK5/6,C8/18,EMA均阴性.结论:MNT是一种罕见的胸腺肿瘤,目前WHO归于交界性,有特殊的发病部位和形态学表现,组织学及免疫组织化学有助于该肿瘤的诊断和鉴别诊断.     

Aggressive fibromatosis of the larynx: report of a new case in an adult patient and review of the literature

We describe a case of aggressive fibromatosis of the larynx occurring in a 75-year-old man. The lesion manifested with voice hoarseness and swallowing difficulty. A computerized tomographic scan of the neck revealed distortion of the glottic profile. A malignant tumor was suspected. Although a laryngoscopy-driven biopsy was non-diagnostic, total laryngectomy was done, since the lesion was not deemed amenable to conservative therapy. Grossly, the glottic rim was infiltrated by a hard, grey-white tissue showing a tentacular outline. Tissue sections featured a moderately cellular lesion composed of spindle cells with bland, tapered nuclei, enmeshed in a variably collagenized ground substance. Delicate spindle cell fascicles surrounded the native submucosal seromucous glands and had invaded the thyroid cartilage and the thyroid gland as well. The spindle cells were immunopositive for actins and vimentin, and negative for keratins, epithelial membrane antigen, desmin, and S-100 protein. No further therapy was administered. Periodic follow-up visits were negative. The patient died 5 years after surgery of myocardial infarction with no clinical evidence of lesion recurrence. Based on the available literature, our data confirm that laryngeal fibromatosis in adult patients is a locally infiltrating and progressive disease. Total laryngectomy with clear margins is needed as to avoid the high risk of local recurrence.     

Immunohistochemical metallothionein expression in thymoma: correlation with histological types and cellular origin

Metallothioneins (MTs) are low molecular weight and cysteine-rich intracellular proteins involved in metal homeostasis and detoxication. They are found in certain normal tissues, and are overexpressed in various tumours with correlation to more aggressive behaviour in certain tumours. Since the histopathological types of thymoma have unpredictable invasive potential, MT over-expression was investigated as a possible marker of the invasive potential of thymomas. We studied immunohistochemical MT expression in 27 non-invasive thymomas, 20 micro-invasive thymomas, and 23 macro-invasive thymomas with a mouse monoclonal anti-MT antibody E9 on formalin-fixed paraffin-embedded tissues. MT expression was significantly different among the three groups of thymomas ( P  = 0.02) with a stronger expression in invasive thymomas ( P  = 0.003). However, MT expression was not exclusively limited to invasive thymomas. Therefore, it could not be used as a marker of aggressive potential in individual thymomas. Analysis of MT expression according to the histological types of the thymomas revealed that eight of nine spindle cell thymomas, none of 10 small polygonal cell thymomas, four of 14 mixed thymomas, seven of 29 large polygonal cell thymomas, and seven of eight squamoid thymomas significantly expressed MT. There was a statistically significant difference in MT expression among different histological types of thymomas ( P  = 0.000). The strongest and most consistent expression was observed in spindle cell thymoma and squamoid thymoma. Since spindle cell thymoma was usually non-invasive and squamoid thymoma was more aggressive, MT expression does not correlate with the invasive potential of different histological types of thymomas. But because medullary epithelial cells of the thymus were positive for MT, our results suggest that both spindle cell thymoma and squamoid thymoma might derive from the medullary compartment of the thymus.     

Primary adenoid squamous cell carcinoma of the oral cavity

Adenoid squamous cell carcinoma (ASCC) is an uncommon but well-recognized variant of squamous cell carcinoma that was first described by Lever in 1947. ASCC has been reported to originate in the sun-exposed skin of the head and neck and in other sites. An additional case of ASCC is reported here. The patient was a 64-year-old Japanese woman who requested examination of a reddish lesion on the left floor of the mouth. The biopsy material was diagnosed as squamous cell carcinoma. Clinical examination showed a well-circumscribed, 20 x 10 mm-sized lesion, which was categorized as cT2cN0cm 0. Tumor resection was therefore performed. Histologically, most parts of the lesion were conventional squamous cell carcinoma in situ, but the invasive part consisted of ASCC with gland-like or reticular appearance. The latter part was negative for mucin staining. Immunohistochemically, this lesion was positive for pancytokeratin, high-molecular-weight keratin, cytokeratin (CK) 7/8, CK19, E-cadherin and p53, but negative for vimentin, CK20, and S-100 protein. The Ki-67 labeling index was 50.3% in the ASCC part and 34.5% in the carcinoma in situ part. These findings and a review of the literature indicate that a gland-like feature of ASCC is associated with the loss of cell adhesion in the center of the cancer nests, and it can be confirmed simply by mucin staining to be neither an adenosquamous carcinoma nor ductal involvement of conventional squamous cell carcinoma.     

Tubulosquam?ser Vaginalpolyp

Tubulosquamous vaginal polyp is a rare form of lesion. It is thought to derive from displaced paraurethral Skene's gland which is the female equivalent of the prostate gland in men. We report on a case of tubulosquamous vaginal polyp in a 77-year-old female patient. Histological examination showed prominent epithelial nests in a spindle cell-rich stroma. The nests were predominantly squamous in type with small tubules at the periphery of the island. Using immunohistochemistry the tubules were found to be positive for CK7, prostate-specific acidic phosphatase (PAP) and androgen receptor (AR) but negative for CK 5/6 and prostate-specific antigen (PSA). The solid parts were positive for CK5/6 and most interestingly, also expressed AR but not CK7, PAP or PSA. The stroma also showed strong staining for AR but not for the other markers applied. To our knowledge this is the first report on AR expression in this benign polyp. Our findings confirm the view that tubulosquamous polyp of the vagina is derived from paraurethral Skene's gland.     

Intramuscular spindle cell lipoma: Case report and review of the literature

Spindle cell lipoma (SCL) is a relatively rare adipocytic neoplasm and is histologically characterized by a mixture of uniform spindle cells and mature fat cells. It occurs predominantly in male patients aged 45-65 years, and in most cases it arises in the subcutaneous tissue of the neck or shoulder. Although the neoplasm sometimes affects unusual sites, only three cases have been reported in which the lesion was intramuscular. Here we present a case of SCL arising in skeletal muscle; to our knowledge, the first report in 10 years. The tumor occurred in the neck of a 50-year-old male patient. Magnetic resonance imaging (MRI) revealed a lipomatous tumor within the right trapezius muscle. The tumor was localized beneath the fascia and was excised completely at surgery. Histologically, the tumor was typical of a spindle cell lipoma with no evidence of malignancy. An immunohistochemical study revealed all spindle cells were strongly positive for CD34. Differential diagnosis is discussed with a review of the literature.     

Fine‐needle aspiration cytology of type A thymoma with adenoid cystic pattern: A case report with emphasis on peculiar hyaline globules in cytologic smear

Here we report a case of type A thymoma with adenoid cystic pattern, which extended to the lower anterior neck and clinically mimicked a nontoxic thyroid goiter. The cytologic smears of fine‐needle aspiration showed cohesive fragments of short spindle cells with finely granular chromatin and inconspicuous nucleoli. Scant interspersed lymphocytes were present. On air‐dried Liu stained preparation, there were many magenta‐colored hyaline globules wrapped by spindle tumor cells. The cytomorphologic findings correlated with the adenoid cystic pattern in histology. The cytologic differential diagnosis and the prognostic aspects of type A thymoma were briefly discussed. Diagn. Cytopathol. 2015;43:247–250. © 2014 Wiley Periodicals, Inc.     

Ectopic cervical thymoma: a mimic of T-lymphoblastic lymphoma

Ectopic cervical thymoma is a rare tumor that probably arises from ectopic thymic tissue trapped during migration of thymic primordia in the embryonic stage. To the best of our knowledge, only 20 cases have been reported. Our patient was a 68-year-old woman who had been suffering from a nodular lesion in the anterior neck for several years. She underwent nearly total right thyroidectomy. Eight years and nine months after surgery, she is free of tumor recurrence or metastasis. The tumor was nodular with fibrous septa, and was composed of varying numbers of epithelial cells and lymphocytes, corresponding to AB thymoma as classified by WHO. Using lymphoid markers only, it was initially misdiagnosed as T-lymphoblastic lymphoma. The lymphocytes expressed T-cell antigens and terminal deoxynucleotidyl transferase and exhibited high proliferation fraction. Awareness of ectopic cervical thymoma, careful microscopic examination, and a proper selection of antibodies for immunohistochemistry will lead to the correct diagnosis.     

Spindle cell lipoma—a pseudoangiomatous variant

Five cases of an unusual pseudoangiomatous variant of spindle cell lipoma are presented. In keeping with more typical cases, these lesions occurred principally in the shoulder and neck regions of adult males. The lesions all had the features of typical spindle cell lipoma but, in addition, exhibited irregular and branching spaces with villiform connective tissue projections, giving a striking angiomatoid appearance. Although the pathogenesis is uncertain, this unusual histological pattern seems to be the result of myxoid degeneration and may lead to a mistaken diagnosis of a true vascular tumour or other non-lipomatous spindle cell lesion.     

Pagetoid bowen disease: a report of 2 cases that express cytokeratin 7

Bowen disease is a variant of squamous cell carcinoma in situ. In some cases a pagetoid growth pattern can be observed with cytologically atypical clear cells arranged singly and in nests. The differential diagnosis of pagetoid Bowen disease includes primarily Paget disease and malignant melanoma in situ, as well as other less common entities. Two cases of pagetoid Bowen disease are described, one in a 65-year-old man with a thigh lesion and the other in a 25-year-old man with a lesion in the penile/scrotal region. Neither patient had clinical evidence of an internal malignant neoplasm. In both cases, the neoplastic cells were positive for cytokeratin (CK) 7 and CK 19 and were negative for CK 18, CK 20, carcinoembryonic antigen, GCDFP-15, c-erbB2, S100, and HMB-45. In aggregate, these findings support the diagnosis of pagetoid Bowen disease. Previously, others have shown that CK 7 is an almost invariable marker of Paget disease. Thus, we report these two cases to illustrate that CK 7 can be expressed by pagetoid Bowen disease and should not be a cause of confusion in the differential diagnosis.     

Spindle-cell non-pleomorphic atypical fibroxanthoma: analysis of a series and delineation of a distinctive variant

Atypical fibroxanthoma is a bizarre, cytologically malignant but usually clinically benign, lesion which typically arises in sun-damaged skin of the head and neck region in the elderly. Classically, its morphology is said to represent the dermal counterpart of pleomorphic malignant fibrous histiocytoma. We have identified 10 cases of a more monomorphic spindle-celled, fascicular variant which, paradoxically, was often mistaken for a clinically malignant lesion because it lacked the pleomorphism of conventional atypical fibroxanthoma. These tumours all arose in the head and neck region as polypoid lesions in the elderly. The tumours were confined to the dermis, often had an epidermal collarette, showed an eosinophilic fascicular morphology and were highly mitotic. All 10 were vimentin positive and five showed very focal actin positivity. Desmin, keratin and S-100 protein were negative in all cases. The clinical course was benign in all cases, justifying their accurate recognition. The principal differential diagnoses are spindle cell squamous carcinoma, spindle cell melanoma and leiomyosarcoma. Immunohistochemistry plays a key role in this distinction.     

Low-grade periductal stromal sarcoma of the breast with myxoid features: Immunohistochemistry

A 52-year-old woman was admitted with a painful right breast tumor measuring more than 20 cm in largest diameter, which ulcerated the overlying skin. The lesion had appeared 4 years previously but the patient hesitated to seek medical care due to 'fear of cancer'. Microscopically, the tumor was composed of spindle cells that formed cuffs around multiple open tubules and ducts set in an abundant, myxoid stroma. The spindle cells had significant atypia with nuclear pleomorphism, occasional cytoplasmic vacuolation and moderate mitotic activity. The ducts and lobules surrounded by the proliferating tumor cells had minimal distortion, with a pericanalicular growth pattern devoid of the phyllodes pattern. The tumor had a multinodular growth pattern with coalesced and individual tumor nodules, the latter being found mostly at the periphery of the lesion. On immunohistochemistry the tumor cells were positive for smooth muscle actin, CD34, and vimentin, and focally positive for CD10. A diagnosis of low-grade periductal stromal sarcoma (PDSS) with myxoid features was established. PDSS is a distinct low-grade breast sarcoma, the appropriate diagnosis of which requires extensive tumor sampling and additional broad immunohistochemistry. PDSS should not be confused with other spindle cell breast tumors because they require different treatment.     

化生性胸腺瘤2例临床病理分析

目的：探讨化生性胸腺瘤的临床及病理学特征。方法：应用光镜及免疫组织化学方法观察2例化生性胸腺瘤的组织学特点及免疫学表型,并复习相关文献。结果：2例均为男性,年龄55岁及56岁。组织学肿瘤显示双相分化特点,上皮细胞区域与梭形细胞区域交错分布并相互移行。上皮细胞呈相互吻合的束状、岛状及宽大的梁状排列,细胞轻度异型,可见核沟及核内假包涵体,偶见核分裂像;梭形细胞呈短束状或席纹状排列,细胞温和,未见核分裂像。免疫表型：上皮细胞区域CK19和AE1/AE3呈强阳性表达,上皮膜抗原（epithelial membrane antigen,EMA）弱阳性;梭形细胞区域表达Vimentin、Bcl-2及CD99,AE1/AE3局灶阳性,EMA弱阳性。两种区域中Ki67指数均〈5%。间质淋巴细胞CD3、CD5、CD20阳性,不表达Td T和CD99。结论：化生性胸腺瘤是一种罕见的良性或低度恶性胸腺肿瘤,诊断依靠病理组织学和免疫组织化学标记,完整切除预后良好。     

Fine needle aspiration cytology of a myoepithelioma presenting as a thyroid nodule

Myoepitheliomas are rare neoplasms that are typically found in the major and minor salivary glands and represent approximately 1.5% of all salivary gland neoplasms. We present a patient with an exophytic anterior midline neck mass, which was initially believed to be a thyroid isthmus nodule that underwent fine needle aspiration (FNA) biopsy. FNA cytologic evaluation reveals numerous plump spindle cells and a myxoid background, thus raising the possibility of rare benign mixed tumor of the thyroid. However, the resected specimen consists of predominately spindle cells with a minor component of chondromyxoid matrix, and no ductal epithelial cells, favoring a diagnosis of myoepithelioma. Although this lesion clinically and radiologically appeared to arise from the thyroid gland, at the time of resection, it was found to be adjacent to the thyroid isthmus and was ultimately diagnosed as a soft tissue myoepithelioma of the midneck. Diagn. Cytopathol. 2015;43:153–157. © 2014 Wiley Periodicals, Inc.