John D. Henley

Malignant Sertoli cell tumors of the testis: a study of 13 examples of a neoplasm frequently misinterpreted as seminoma.

The distinction of Sertoli cell tumors from seminoma is critical to ensure proper treatment. Although usually straightforward, we highlight herein 13 malignant Sertoli cell tumors of the testis with light microscopic features that mimicked seminoma. All of the cases were received in consultation, 10 with submitting diagnoses of seminoma, usually of classic type, but three cases of spermatocytic type. Patients ranged from 15 to 80 years of age (median 37 years); all presented with testicular masses. The tumors were typically firm, white to yellow–tan, and often had foci of hemorrhage. The dominant microscopic pattern was nested or sheet-like, with some tumors having secondary patterns of trabeculae–solid tubules, hollow tubules, and pseudofollicles. Tumor cells were polygonal with conspicuous clear cytoplasm in 12 cases; the cytoplasm was focally eosinophilic in 10 cases, but this was never conspicuous. Nine tumors had cytoplasmic vacuoles, and three of four that were investigated stained for intracytoplasmic glycogen. Nuclei were small (5) to medium-sized (8), round-to-oval (13), and vesicular with irregular contours (11). Nucleoli were present in 11 tumors (six small; five large). Stromal fibrosis (12) and lymphoid infiltrates (10) were conspicuous, and tumor necrosis (11) and vascular invasion (8) also were seen. Mitotic figures ranged from <1 to 21/10 high power fields (HPF) (median 1/10 HPF). Staining for inhibin-&agr;, epithelial membrane antigen, and cytokeratin (AE1/AE3) was positive in four of four, six of six, and three of six cases, respectively; placental alkaline phosphatase was negative in all five tumors investigated. The nested growth pattern, prominence of clear cells, lymphoid infiltrate, inconspicuous tubular differentiation, cytoplasmic glycogen, and prominent nucleoli caused these tumors to be mistaken for seminomas. The smaller, less pleomorphic nuclei of Sertoli cell tumors, their lower mitotic rate, and the absence of intratubular germ cell neoplasia are helpful differential features. Immunohistochemistry is a useful adjunct in confirming the diagnosis of Sertoli cell tumor, but only if the overlapping features are appreciated by conventional microscopy and the diagnosis of Sertoli cell tumor included in the differential.

Tyrosine kinase receptor expression in thymomas.

PurposePromising new therapies for neoplasia include tyrosine kinase receptor antagonists. Tyrosine kinase oncogenes present an appealing anti-tumor drug target since they play an integral role in a variety of cellular responses including cell proliferation and differentiation. We previously demonstrated a high rate of epidermal growth factor receptor (EGFR) expression in advanced-stage thymic epithelial tumors. More recently, we have examined c-KIT (CD117) expression in a similar series of tumors.MethodsTumor from 35 patients seen at our institution for treatment of advanced-stage thymoma was available. Twenty thymomas and 15 thymic carcinomas were assessed for c-KIT expression. Tissue sections of tumor were stained immunohistochemically with anti-c-KIT (Oncogene). Either cytoplasmic or membrane staining was considered positive. Appropriate controls were performed. Positive staining for c-KIT was present in 12 tumors (11 thymic carcinomas and 1 thymoma).ResultsIn distinction to EGFR, c-KIT is expressed more commonly in thymic carcinomas (73% of carcinomas) than in thymoma (5% of thymomas).ConclusionsAn EGFR negative/c-KIT positive staining pattern is typical of thymic carcinoma, whereas thymomas are generally EGFR positive/c-KIT negative. Possible therapeutic implications of these observations remain to be determined.

Identical Allelic Losses in Mature Teratoma and Other Histologic Components of Malignant Mixed Germ Cell Tumors of the Testis

Teratomas of the testis in post-pubertal patients are histologically diverse tumors that often coexist with other types of germ cell tumors. Using laser capture microdissection and loss of heterozygosity analysis, we investigated the clonality of mature teratoma and its relationship to other components of malignant mixed germ cell tumors to gain potential insight into the histogenetic relationship of teratoma with other germ cell tumor components. All 16 patients had mature teratoma as one component of their mixed germ cell tumors. The other histological subtypes included immature teratoma, seminoma, embryonal carcinoma, yolk sac tumor, and choriocarcinoma. Laser-assisted microdissection was performed on the formalin-fixed, paraffin-embedded tissue. Polymerase chain reaction was used to amplify genomic DNA at specific loci on chromosome 1p36.2 (D1S508), 2q22-32 (D2S156), 9p21-22 (D9S162), 11p13 (D11S903), 12q22-23 (D12S1051), and 18q21 (D18S46). Fourteen of 16 (88%) cases showed allelic loss in one or more components of the mixed germ cell tumors. Fourteen of 16 mature teratomas showed allelic loss in at least one of six microsatellite polymorphic markers analyzed. The frequency of allelic loss in mature teratoma was 50% (7 of 14) with D1S508, 33% (5 of 15) with D2S156, 58% (7 of 12) with D9S162, 43% (6 of 14) with D11S903, 20% (3 of 15) with D12S1051, and 33% (5 of 15) with D18S46. Completely concordant allelic loss patterns between mature teratoma and all of the other germ cell tumor components were seen in 10 of 14 tumors in which mature teratoma showed loss of heterozygosity. Our data support the common clonal origin of mature teratoma with other components of malignant mixed germ cell tumors of the testis.

Seminomas with exclusive intertubular growth: A report of 12 clinically and grossly inconspicuous tumors

Intertubular growth in seminoma is characterized by seminoma cells, either singly or in small clusters, between preserved seminiferous tubules. It is a common, although focal, pattern in many seminomas where it is admixed with the usual sheet-like and nested arrangements and does not pose any diagnostic problems in such cases. We describe, in contrast, the clinicopathologic features of 12 cases with exclusively intertubular growth and which were typically diagnostically problematic. The 12 patients lacked overt clinical signs of a primary testicular mass. Three presented with infertility, 2 with cryptorchidism, 2 with metastases, 1 with pain and testicular atrophy, and the presentation was unknown in 4. On gross examination, no mass was apparent in 9 cases with available data, but ill-defined firm areas or foci of whitish-brown discoloration were occasionally noted. Microscopically, the process was characterized by individual, dispersed tumor cells or small clusters of cells growing between the seminiferous tubules. The tumor cells were often obscured by a lymphocytic infiltrate or, less commonly, nodules of hyperplastic Leydig cells. Common associated findings were tubular atrophy with sclerosis and thickening of tubular basement membranes and intratubular germ cell neoplasia, unclassified type. Immunostains against placental-like alkaline phosphatase and c-KIT (CD117) highlighted the seminoma cells in all cases examined. In pure form, intertubular seminoma is both clinically and pathologically inconspicuous and may be misdiagnosed as atrophy, scar, or orchitis.

Extrathoracic metastases of thymic origin: a review of 35 cases.

Thymic tumors are categorized as types A, AB, B1, B2, B3, and thymic carcinoma under the World Health Organization (WHO) classification. Thymomas are typically slow growing tumors that predominantly involve the surrounding structures through direct invasion, while thymic carcinomas tend to be more aggressive. A significant number of patients are asymptomatic and can present with metastases as the first presentation. The exact incidence of extrathoracic metastases from thymoma is not known. This study describes a series of 35 cases of histologically documented metastatic thymomas and thymic carcinomas at extrathoracic sites. These cases were classified according to the current World Health Organization (WHO) classification criteria, and we present their clinical data as well as discuss the differential diagnoses of these lesions. Our study shows that all types of thymic tumors, regardless of histologic type, can be associated with invasion and metastases to thoracic and extrathoracic sites.

Prognostic indicators after surgery for thymoma.

BACKGROUND We undertook a 20-year retrospective institutional study to investigate prognostic indicators after surgery for thymoma. METHODS From 1989 to 2009, 83 patients underwent surgical resection of thymoma or thymic carcinoma at our institution. Twelve of these patients were determined to have either World Health Organization type C disease or Masaoka stage IV-B disease and were excluded from analysis. The remaining 71 patients were reviewed. RESULTS The majority of patients in this series were female 64.7% (n=46) with an overall average age of 51.0 years. The distribution of Masaoka stages I, II, III, and IV-A was 40.8% (n=29), 19.7% (n=14), 18.3% (n=13), and 21.1% (n=15), respectively. Thirteen of the 28 (46.2%) patients who presented with stage III or IV-A disease received preoperative chemotherapy. After a mean follow-up of 66 months (range, 6 to 241 months), 54 (75.3%) patients are alive and well while six are alive with disease. Eleven (16.0%) patients have died, but only 3 (4.3%) of these patients died of thymoma. The overall disease-specific survival was 97% and 89% at 5 and 10 years. Of the variables analyzed, only age was predictive of overall survival (p=0.03). Masaoka stages I to III as compared with stage IV-A was significantly predictive of disease-free survival (p<0.01). CONCLUSIONS Long-term disease-specific survival can be expected not only after surgery for early stage thymoma but also after surgery for advanced disease, including patients with pleural metastases. However, patients who undergo surgery for stage IV-A disease have reduced disease-free survival. Late mortality due to secondary cancers and associated immunologic disorders was more frequent than mortality from thymoma in this series.

WHO types A and AB thymomas: not always benign

The 2004 WHO classification of thymic tumors recognizes five major subtypes of thymomas and thymic carcinoma. Subtypes A and AB thymomas are purported to be benign neoplasms, although prior studies have suggested a potential for malignant behavior. The purpose of this study was to assess the clinical behavior of A and AB thymomas identified from a large institutional pathologic database. A retrospective slide review of 500 thymic epithelial tumors identified 71 (∼14%) cases of types A and AB thymomas. Clinical history and follow-up information were obtained through retrospective chart review. There were 38 and 33 cases of types A and AB thymomas, respectively. Complete follow-up data were available in 37 (52%) cases. Eighteen (49%) patients (type A, n=9 and type AB, n=9) had evidence of recurrent/metastatic disease at an average of 62 months (range from 6 to 244 months) after initial diagnosis. Survival curves for patients with types A and AB thymomas, with and without recurrences, show a statistically significant difference (P=0.001 and 0.005, respectively). Analysis of this large cohort confirms the potential for subtypes A and AB thymomas to show malignant behavior. Long-term clinical monitoring, therefore, appears to be justified in these cases. This study also shows the poor correlation between the WHO classification and tumor behavior

Diagnostic utility of thymic epithelial markers CD205 (DEC205) and Foxn1 in thymic epithelial neoplasms.

Foxn1 and CD205 (DEC205) are novel thymic epithelial markers that are important for thymic organogenesis and the positive selection process for thymocytes, respectively. These markers were immunohistochemically applied to a total of 77 cases of thymic epithelial neoplasms comprised of 58 cases of thymomas, 17 cases of thymic carcinomas, and 2 cases of thymic neuroendocrine carcinomas. Foxn1 was diffusely expressed in nuclear staining in all cases of type B thymoma and all but 1 case of type A thymoma, whereas the expression was generally focal in thymic carcinoma (76%). The expression was identified in all cases of mixed AB thymoma, with the expression in type A component being more variable than the one in type B component. CD205 cytoplasmic expression in the form of coarse granular staining with membranous accentuation was strong and diffuse in all cases of type B thymoma (100%), and a majority of type A thymoma (89%), and focal with variable intensity in thymic carcinoma (59%). Mixed AB thymoma demonstrated diffuse expression in type B component (100%), and variable expression in type A component (94%). Neither Foxn1 nor CD205 was expressed in 2 cases of thymic neuroendocrine carcinoma. Foxn1 was focally expressed in 13% of cutaneous squamous cell carcinoma and completely negative in cutaneous basal cell carcinoma, whereas it was completely negative in squamous cell carcinoma from head and neck, esophagus and uterine cervix, and normal tissue and malignant neoplasms from all other organs other than thymus. CD205 was expressed in 4% of nonsmall cell carcinomas of lung, 27% of squamous cell carcinoma of head and neck, and 10% of squamous cell carcinoma of esophagus, but the staining pattern was different from that of thymic epithelial neoplasm and was characterized by rather homogeneous and amorphous quality without granularity or membranous reaction. CD205 was expressed in myeloid dendritic cells of various organs and tissues as well. Foxn1 is a sensitive and specific marker for thymoma and thymic carcinoma, and it appears to be superior to CD5 and CD117 for the diagnosis of thymic carcinoma. CD205 is a sensitive and specific marker for thymoma but its sensitivity to thymic carcinoma is lower than CD5 and CD117.

Spindle cell lipoma of the oral cavity.

Spindle cell lipoma is typically seen in the neck/trunk region of middle-aged and older men. Rare cases of oral spindle cell lipoma have been reported. An entity described as myxoid lipoma of the oral cavity has rarely been reported but appears to be more properly classified as spindle cell lipoma. We describe the largest series yet of oral spindle cell lipoma involving the tongue (4), buccal mucosa (1), floor of mouth (1), and lip (1). The patients (3M; 4F) ranged from 31 to 88 years old. All presented with mass lesions. All were circumscribed and composed of mature adipocytes admixed with bland spindled cells. In two cases the adipocytes appeared atrophic, imparting a pseudo-lipoblastic appearance. No true lipoblasts were seen and none had the characteristic vasculature of a myxoid liposarcoma or the characteristic hyperchromatic cells of well-differentiated liposarcoma. The stromal background of all cases contained characteristic wiry collagen and myxoid ground substance. The myxoid ground substance was prominent in four cases. Immunohistochemical stains for CD34 highlighted the bland spindle cells in all cases. The combination of the histologic features and the immunoreactivity for CD34 confirmed the diagnosis. Spindle cell lipoma should be considered in the differential diagnosis of oral cavity mesenchymal tumors.

Cystic trophoblastic tumor: a nonaggressive lesion in postchemotherapy resections of patients with testicular germ cell tumors.

Cystic trophoblastic tumor (CTT) is an uncommon lesion that is usually seen after chemotherapy in patients with testicular germ cell tumors. Its clinical significance has not been well studied. We identified 17 patients with CTT in retroperitoneal lymph node dissections (RPLNDs) after cisplatin-based chemotherapy for testicular germ cell tumors. None had other forms of persistent germ cell tumor except for teratoma, and no patient received additional chemotherapy after RPLND. At the time of RPLND, 7 patients were known to have had normal serum levels of β-subunit of human chorionic gonadotropin (β-hCG), whereas 5 had relatively mild elevations (1.6–165 mIU/mL, median, 8.0 mIU/mL). The CTTs consisted of circumscribed, small cysts, usually multifocal, lined by mostly mononucleated trophoblast cells with abundant eosinophilic cytoplasm, often with smudged nuclei and showing only infrequent mitotic figures. Although the epithelial lining was often stratified to several layers in thickness or formed intracystic papillary tufts, solid proliferations of trophoblast cells within the stroma were absent, as were clearly biphasic admixtures of mononucleated and multinucleated trophoblast cells. The cysts were either empty or contained fibrinoid material and were set in a hypocellular, fibrous stroma with adjacent teratoma. Stains for hCG highlighted rare cells. On follow-up of 15 patients, 11 were disease free (mean, 80 months). Three recurred with serum alpha-fetoprotein elevations at 25, 31, and 107 months, respectively, and one with β-hCG elevation at 2 months. The latter patient, however, also had unresected mediastinal tumor postchemotherapy. We conclude that the finding of CTT in postchemotherapy resections does not warrant additional chemotherapy. Its clinical significance appears similar to that of residual teratoma.