Adenocarcinoma of the uterine cervix with choriocarcinomatous and hepatoid differentiation: report of a case

Primary Peritoneal Hepatoid Adenocarcinoma Patients Treated by Complete Cytoreductive Surgery (CRS) and Hyperthermic Intraperitoneal Chemotherapy (HIPEC)

Hepatoid adenocarcinoma (HAC) is an extremely rare disease, which could develop from any thoraco-abdominal organ and which exhibits features mimicking hepatocellular carcinoma (HCC). Its diagnosis is thus highly challenging, so is the treatment of that disease. So far, 12 cases have been reported in the literature as issued from the peritoneum. These primary peritoneal HAC were associated with a dismal prognosis and heterogenous management. Two additional cases were described here, managed in a multidisciplinary way as rare peritoneal surface malignancies in an expert center, following the strategy based on a comprehensive tumor burden extension assessment and a radical approach combining iterative complete cytoreductive surgeries followed by hyperthermic intra-peritoneal chemotherapy (HIPEC) and limited systemic chemotherapy sequences. In particular, the choline PET-CT scan guided surgical exploration to reach a complete resection. The oncologic outcomes were promising with a first patient dying 111 months after the diagnosis and a second patient still alive at 43 months.

Hepatoid adenocarcinoma-Clinicopathological features and molecular characteristics

Hepatoid adenocarcinoma (HAC) is a rare, malignant, extrahepatic tumor with histologic features similar to those of hepatocellular carcinoma. HAC is most often associated with elevated alpha-fetoprotein (AFP). HAC can occur in multiple organs, including the stomach, esophagus, colon, pancreas, lungs, and ovaries. HAC differs greatly from typical adenocarcinoma in terms of its biological aggression, poor prognosis, and clinicopathological characteristics. However, the mechanisms underlying its development and invasive metastasis remain unclear. The purpose of this review was to summarize the clinicopathological features, molecular traits, and molecular mechanisms driving the malignant phenotype of HAC, in order to support the clinical diagnosis and treatment of HAC.

Morphological and molecular pathological features of the breast carcinoma with choriocarcinomatous features: A case report and a literature review

Here we present a rare case of breast cancer with both invasive ductal carcinoma and choriocarcinoma components in a 55-year-old woman. Firstly, the serum human chorionic gonadotropin level showed 15.9mIU/ml preoperatively. And adequate immunohistochemical tests were performed on the specimen. Secondly, High-throughput sequencing was performed to detect the molecular characteristics of the two components, respectively. Then, DNA short tandem repeat (STR) analysis confirmed the homology of the two components, indicating the somatic origin of choriocarcinoma components. Finally, the clinical course and pathological characteristics of the case were reviewed and a literature search for other cases was performed.

Fluorescence In Situ Hybridization for the X and Y Chromosome Centromeres Helps Differentiate Between Gestational and Nongestational Choriocarcinoma in Clinically Ambiguous Cases

CONTEXT.—

Gestational choriocarcinoma usually presents during the reproductive years, typically within 1 year of pregnancy, although presentation remote from pregnancy also occurs and may cause confusion with other tumors, including choriocarcinoma of germ cell origin and somatic carcinomas with choriocarcinomatous differentiation. It is important to separate these tumors for treatment and prognostic reasons.

OBJECTIVE.—

To assess the utility of fluorescence in situ hybridization for the X and Y chromosome centromeres in determining the gestational origin of clinically ambiguous extrauterine choriocarcinomas in women.

DESIGN.—

A review of female patients with extrauterine choriocarcinomas who had no evidence of prior gestational trophoblastic disease was performed. Samples were analyzed by fluorescence in situ hybridization for the X and Y chromosome centromeres using standard methodologies.

RESULTS.—

Five cases met the criteria, all of which displayed trophoblastic cells and necrosis. Three cases (60%) had Y chromosomes by fluorescence in situ hybridization, which confirmed gestational origin. Although the 2 cases without a Y chromosome would ordinarily require molecular genotyping for paternal genetic material to establish gestational origin, in one of these cases a subsequent recurrence of yolk sac tumor allowed confirmation of its mediastinal origin.

CONCLUSIONS.—

Fluorescence in situ hybridization for detection of the X and Y chromosome centromeres is an effective screening test for gestational choriocarcinoma. It provided a definitive diagnosis of metastatic gestational choriocarcinoma in 3 of 5 potential cases that lacked a clinical history of gestational trophoblastic disease. An additional benefit is that more laboratories have the capability to perform fluorescence in situ hybridization than can perform molecular genotyping for definitive diagnosis.

Hepatoid carcinoma of the pancreas: A case report and review of the literature

BACKGROUND

Hepatoid carcinoma (HC) is an extremely rare neoplasm that is morphologically similar to hepatocellular carcinoma. HC has been described in various organs; however, HC of the pancreas is extremely rare. To our knowledge, only 38 cases have been reported. We present a case of HC of the pancreas in a 36-year-old male patient.

CASE SUMMARY

A 36-year-old cachexic man with no significant past medical history was transferred to our hospital with a history of painless jaundice, elevated blood glucose and significant weight loss. Lab tests showed elevated serum transaminases, bilirubin and alpha-fetoprotein levels. Magnetic resonance imaging of the upper abdomen showed a diffusely enlarged pancreas, appearing “sausage-shaped”. Magnetic resonance cholangiopancreatography showed upstream ductal dilation secondary to stricture of the main pancreatic duct and the common bile duct, which were not visible. Immunohistochemistry of biopsied tissue from a percutaneous pancreatic biopsy showed tumor cell positivity for HepPar1, polyclonal carcinoembryonic antigen and CK19, suggestive of HC of the pancreas. The characteristics of 39 patients with HC of the pancreas were reviewed.

CONCLUSION

HC of the pancreas is more prevalent in males, and patients have a median age of 57 years. It is most commonly asymptomatic or presents as abdominal back pain, and the pancreatic tail is the most common location. At the time of diagnosis, liver metastasis is often present.

Clear Cell Carcinoma of the Cervix With Choriocarcinomatous Differentiation: Report of an Extremely Rare Phenomenon Associated With Mismatch Repair Protein Abnormality

The presence of trophoblastic differentiation or nongestational choriocarcinoma in a carcinoma is rare but has been described in various organs, including in the female genital tract. We report a cervical clear cell carcinoma admixed with a component of choriocarcinoma in a 52-year-old woman, only the second report of this combination in the literature. Immunohistochemically, the tumor exhibited isolated loss of staining with the mismatch repair protein MSH6. We review the literature on trophoblastic differentiation in cervical carcinoma.

Hormone producing gynecological tumors: pathologic entities and clinical significance

INTRODUCTION

Due to their derivation from the cell types involved in gynecologic hormonal networks, many gynecologic tumors may produce hormones. In a normal physiological setting, these hormones are essential for regulating the biology and function of gynecological organs, the ovary and uterus in particular. Overproduction of hormones by the tumor may lead to abnormal clinical manifestations of the patients and spillage of excess hormonal products into the blood. Abnormal elevation of serum hormones may be considered as biomarkers that are important to pathologists and clinicians in making precise tumor diagnoses and likely useful in monitoring the tumor burden/recurrence to guide patient treatment options. This review will discuss gynecologic neoplasms that produce hormonal biomarkers and assess their relevance to pathological diagnosis, evaluation for therapeutic response and monitoring disease progression.

AREAS COVERED

Studies involving hormonal production by a gynecologic tumor were candidates for inclusion in this review.

EXPERT COMMENTARY

Serum hormonal biomarkers have clinical utility both in the diagnosis of gynecologic neoplasms and clinical monitoring of treatment efficacy and recurrence.

Establishment and biological characterization of a novel cell line derived from hepatoid adenocarcinoma originated at the ampulla of Vater

Hepatoid adenocarcinoma is a rare gastrointestinal tumor and mostly reported in the stomach. Effective chemotherapy has yet to be developed to improve poor prognosis. The present study was undertaken to establish a useful cell line derived from a hepatoid adenocarcinoma, possibly leading to a new therapeutic strategy. The new human cell line VAT-39 was established from a metastatic lymph node of a 69-year-old Japanese male patient with hepatoid adenocarcinoma of the ampulla of Vater. The primary tumor and metastatic lymph node were composed of hepatoid adenocarcinoma cells exhibiting immunohistochemical reactivity for alpha-fetoprotein (AFP) and glypican-3 (GPC3). In the metastatic lymph node, Periodic acid-Schiff (PAS) staining clarified diffuse deposition of glycogen in the cytoplasm, indicating analogous characteristics to the primary hepatoid adenocarcinoma. Moreover, VAT-39 cells produced high levels of AFP in the cultured medium, and reverse-transcriptase polymerase chain reaction (RT-PCR) verified increased expression of GPC3 mRNA in this cell line. Further, we evaluated the sensitivity to major chemotherapeutic drugs against the bile duct cancer. Neither 5-fluorouracil nor gemcitabine showed particular sensitivity to this cell line. The tumorigenicity of the cultured cells was confirmed in athymic nude mice and the histological features of the explanted tumor were similar to the VAT-39 cell line. The present VAT-39 is the first hepatoid adenocarcinoma cell line that originates from the ampulla of Vater and it will be applicable for basic biological studies searching for new strategies of molecular targeted chemotherapy to this disease.

Endometrioid adenocarcinoma with choriocarcinomatous differentiation: A case report and review of the literature

A choriocarcinomatous component is rarely present in carcinomas of certain sites and few cases of choriocarcinomatous differentiation in endometrioid adenocarcinoma have been reported. The present study reports a case of endometrioid adenocarcinoma of the uterine corpus with choriocarcinomatous differentiation, and discusses the clinicopathological features of this rare tumor. A 59-year-old post-menopausal female presented with abnormal vaginal bleeding. Magnetic resonance imaging demonstrated a relatively well-circumscribed tumor in the uterine corpus and a total cystectomy was subsequently performed. A histopathological examination revealed two distinct components in the uterine corpus tumor. The first component comprised ~80% of the tumor and was composed of poorly-differentiated endometrioid adenocarcinoma. The remaining component consisted of mononucleated and syncytial giant cells containing rich eosinophilic cytoplasm and large pleomorphic nuclei with coarse chromatin. An immunohistochemical analysis revealed that these syncytial giant cells were positive for β-human chorionic gonadotropin (hCG). Therefore, a diagnosis of endometrioid adenocarcinoma with choriocarcinomatous differentiation was confirmed. The clinicopathological features of nine previously reported cases of this tumor were analyzed in addition to the present case. The majority of the patients were post-menopausal. Endometrial choriocarcinoma may be considered to have a highly aggressive clinical course, since nine of the 10 cases displayed metastases and four patients succumbed to the disease. The pathogenesis of the choriocarcinomatous component is not well understood. However, genetic studies have demonstrated that conventional carcinoma and choriocarcinomatous components share common genetic alterations. The choriocarcinomatous component represents aberrant differentiation of the conventional carcinoma, however, genetic analyses of endometrioid adenocarcinoma with choriocarcinomatous differentiation have not been performed.

A rare case of metastatic pancreatic hepatoid carcinoma treated with sorafenib

BACKGROUND

Hepatoid carcinoma (HC) is a rare histopathological tumor type with prominent features of hepatoid differentiation, and while most of the reported cases are of gastric origin, ten cases of pancreatic HC have been reported to date. The majority of HC cases are metastatic at presentation, mainly to the liver, lymph nodes, and lungs. They are aggressive, invading, and proliferating in the venous and lymphatic systems, with a behavior similar to that of hepatocellular carcinoma. Diagnosis is challenging: alpha-Fetoprotein, the most useful marker, is not always positive.

METHODS

We present the first case of metastatic pancreatic HC treated with sorafenib, an oral multikinase inhibitor approved for advanced hepatocellular carcinoma that has antiangiogenic, pro-apoptotic, and raf-kinase inhibitory properties.

RESULTS

The patient, a 37-year-old male, was diagnosed with hepatoid carcinoma of the pancreas that had metastasized to liver, lungs, and lymph nodes. The cytokeratin (CK) profile was useful for the diagnosis: Both the hepatoid and adenocarcinoma components of the tumors were CK18+, CK19+, and CK20+/-, whereas normal and neoplastic hepatocytes are CK18+, CK19-, and CK20-. Amylase, lipase, and liver enzyme levels were elevated, but bilirubin was normal. Treatment with sorafenib resulted in more than 7 months of progression-free survival. Therapy was discontinued after 8 months when his bilirubin level increased dramatically. Signs of liver failure resolved temporarily with insertion of a biliary stent, but his condition deteriorated and he died 3 months later, 1 year after diagnosis.

CONCLUSION

In the absence of evidence-based experience with this rare and aggressive tumor and given its similarities with hepatocellular carcinoma, sorafenib should be considered as a possible treatment.

Endometrial carcinoma with choriocarcinomatous differentiation: a case report and review of the literature

BACKGROUND

Choriocarcinomas unrelated to pregnancy, teratomas, or germ cell tumors have been found in the stomach, lungs, colon, esophagus, bladder, breast, renal pelvis and other sites.

CASE

We present a case of a 58-year-old woman with endometrial carcinoma with choriocarcinomatous differentiation. She received surgery and chemotherapy for endometrial adenocarcinoma. However, a metastatic tumor of choriocarcinomatous element appeared at the vaginal cuff 9 months after surgery. Additional chemotherapy for choriocarcinoma resulted in a decrease in the serum hCG and the tumor regressed. Fifty months following surgery, she is alive without disease.

CONCLUSION

Treatment and follow-up must be performed not only for the adenocarcinoma element but also for the choriocarcinoma element in patients presenting with endometrial carcinoma with choriocarcinomatous differentiation.

Hepatoid adenocarcinoma of the gallbladder: a mimicker of hepatocellular carcinoma

We present a case of a large gallbladder tumour in a patient with no known liver disease and elevated alpha-fetoprotein (AFP), in whom a differential diagnosis from hepatocellular carcinoma (HCC) in a non-cirrhotic liver was particularly difficult given the combination of the size of the tumour, solitary nature, elevated AFP and striking resemblance with HCC at histology. In presenting this patient, we would like to emphasise the role of MRI as a problem-solving tool for analysis of rare tumours of non-hepatocellular origin, including hepatoid adenocarcinoma of the gallbladder.

Endometrioid carcinoma of the endometrium with choriocarcinomatous differentiation: a case report and review of the literature

OBJECTIVE

An endometrioid adenocarcinoma (EAC) with true trophoblastic differentiation is a rare event with a highly aggressive clinical course.

CASE

We report an endometrioid adenocarcinoma of the endometrium in which there was a morphologically conventional-appearing EAC component admixed with multinucleated giant cells and large pleomorphic tumor cells that resembled a choriocarcinoma without an elevated serum level of human chorionic gonadotropin (hCG) in a 42-year-old unmarried woman with a history of abnormal uterine bleeding. A total abdominal hysterectomy, bilateral salpingo-oophorectomy, and pelvic lymph node dissection were performed. Histopathologic study of the specimen showed endometrioid adenocarcinoma extended to the deep myometrium with a focus of hemorrhagic and necrotic tumor composed of multinucleated giant cells, large pleomorphic tumor cells, suggesting choriocarcinomatous differentiation (CD). Immunohistochemical studies demonstrated intense reactivity of tumor cells for human chorionic gonadotropin (hCG) confirming the diagnosis. A complete clinical workup ruled out metastatic spread to the brain, lungs, skeleton, or abdomen. The patient was alive with no evidence of disease 6 months later.

CONCLUSION

Although endometrioid adenocarcinoma with choriocarcinomatous differentiation is known to behave in a more aggressive course, this disease may have a good prognosis with a clinically indolent course when it is small, and without elevated serum hCG levels.

Primary hepatoid adenocarcinoma of the uterine cervix

Hepatoid adenocarcinoma is characterized histologically by neoplastic epithelial cells that resemble hepatocellular carcinoma (HCC) and produce alpha-fetoprotein (AFP). We describe a case of hepatoid adenocarcinoma of the uterus that, unlike any other previously reported case, was strictly confined to the cervix. A cervical biopsy demonstrated poorly differentiated adenocarcinoma, and hysterectomy and bilateral salpingo-oophorectomy were subsequently performed. Histologically, the lesion consisted of solid sheets of hepatoid cells accompanied with areas of endometroid adenocarcinoma. The tumor cells showed strong and diffuse cytoplasmic immunoreactivity with AFP in both medullary and adenocarcinoma components. Metastases to bilateral pelvic lymph nodes were detected 12 months after surgery. Since undergoing total pelvic irradiation, the patient has been alive and in full remission for 22 months. To our knowledge, this is the first report of primary hepatoid adenocarcinoma of the uterine cervix.

Hepatoid carcinoma of the pancreas: a case report and literature review of a heterogeneous group of tumors

Hepatoid carcinomas are tumors that display, at least focally, cytologic and/or architectural features of hepatocellular carcinoma. They have been described in several organs, most notably in the stomach and ovary. We report a case of hepatoid carcinoma of the pancreas that developed in a 41-year-old woman in association with a pancreatic endocrine carcinoma. The fine needle aspiration material was characterized by the presence of monotonous, small-to-medium sized tumor cells with round nuclei and finely granular chromatin, intermixed with more atypical tumor cells displaying larger nuclei with coarse clumped chromatin, prominent nucleoli, and moderate amounts of foamy cytoplasm. The excised specimen displayed a poorly differentiated pancreatic endocrine carcinoma associated with well-defined islands of larger tumor cells growing in a perisinusoidal pattern which, based on their immunohistochemical profile and the demonstration of bile, proved to represent a hepatoid component. This case and prior examples in the literature suggest that hepatoid carcinomas of the pancreas appear to be a heterogeneous group of tumors (pure or associated with another histologic component) that are often associated with early liver metastasis and a short survival, although those arising as a component of endocrine tumors seem to fare slightly better. Hepatoid carcinoma of the pancreas should be included in the differential diagnosis of pancreatic tumors composed of large eosinophilic cells.

Adenocarcinoma of the uterine cervix with choriocarcinomatous metastasis

BACKGROUND

Nongestational choriocarcinoma, in very rare instances, has been described as a component of other malignancies with a tendency for a very poor prognosis.

CASE

A 55 year old woman was diagnosed with adenocarcinoma of the cervix, and incompletely treated with only external beam radiation. Adjuvant radical hysterectomy demonstrated no residual tumor, but the patient developed a tumor metastasis mimicking a pulmonary artery thrombus which by histology and immunohistochemistry was pure choriocarcinoma. While chemotherapy was successful in achieving a complete remission, the patient succumbed to complications of her pulmonary metastasis.

CONCLUSION

Choriocarcinomatous dedifferentiation of cervical adenocarcinoma is extremely rare, with only one other case reported in the literature. While the prognosis for patients with such a tumor is generally poor, aggressive combination chemotherapy may be of benefit in some.

Hepatoid carcinoma of the pancreas

Background

Hepatoid carcinoma of the pancreas is extremely rare. This article tries to summarize the clinical features and outcomes of pancreatic hepatoid carcinoma.

Methods

The data pool for analysis includes the case we encountered with hepatoid carcinoma of the pancreas and the reported cases in the literature.

Results

Twenty-three cases of hepatoid carcinoma of the pancreas were analyzed. This tumor occurred more frequently in male than in female patients (69.6 vs. 30.4 %). Tumor sizes range from 0.5 to 11.0 cm with median of 6.0 cm. The most common symptom was epigastric pain (36.4 %). When the tumor locates at pancreatic head, nausea/vomiting (62.5 %) is more common, followed by jaundice and epigastric pain (50.0 %). For those at pancreatic body-tail, 42.9 % of the patients presented no symptom. Alpha-fetoprotein (AFP) was abnormally elevated in 60 % of the cases. Hepatoid carcinoma in the pancreas could be either pure form or mixed form with other malignancy (40.9 %), with the most common coexisted pathology of malignant neuroendocrine tumor (22.7 %). Metastasis occurred in 36.4 % of the cases at the diagnosis of this tumor, including liver metastasis in 31.8 % and lymph node metastasis in 21.1 %. The overall 1-year survival rate was 71.1 % and 5-year 40.4 %, with a median of 13.0 months. Unresectability, hepatic, and lymph node metastases are associated with negative impact on survival outcome.

Conclusions

Elevation of serum AFP may be a clue leading to the diagnosis of pancreatic hepatoid carcinoma. This tumor could be mixed form with other malignancy. Surgical resection should be the treatment of choice whenever possible.

Hepatoid adenocarcinoma of the stomach

A 54-year-old man presented to his doctor with hematemesis and was found at endoscopy to have an ulcerated lesion in his stomach. A computed tomography scan was performed and revealed a mass in the fundus of the stomach. Multiple other lesions were identified in the liver, lungs, retroperitoneal space, and mesentery. Gross examination showed two separate gastric lesions containing nests and single cells with mucin intermixed with sheets of tumor cells with abundant eosinophilic cytoplasm invading throughout the wall of the stomach. Immunohistochemical studies were performed and the cells were positive for hepatocyte, MOC 31, cytokeratin A1/A3, and CK 7, and were negative for CK 20, alpha-fetoprotein, and thyroid transcription factor. The histologic features together with the immunohistochemical findings were diagnostic of a hepatoid adenocarcinoma of the stomach. Hepatoid adenocarcinoma is a rare tumor associated with a very poor prognosis. Immunohistochemical studies may help to identify the characteristic features of hepatoid differentiation and prevent mistaking this tumor for other types of carcinoma.

Hep Par 1 expression in carcinoma of the cervix: implications for diagnosis and prognosis

AIMS

To determine the frequency and pattern of Hep Par 1 expression in cervical carcinomas of various histological types and to correlate expression with prognostic parameters.

METHODS

Twenty nine cervical carcinomas were analysed for tumour type, hepatoid and neuroendocrine differentiation, and vascular invasion. A semiquantitative analysis was performed for Hep Par 1, alpha fetoprotein, chromogranin, and synaptophysin immunoreactivity.

RESULTS

Hep Par 1 expression was seen in seven of the 29 cervical carcinomas (three of seven adenocarcinomas, one of 17 squamous cell carcinomas, one of two adenocarcinomas with adenocarcinoma in situ, one of two adenocarcinomas in situ, and one of one large cell neuroendocrine carcinoma with adenocarcinoma in situ). Normal looking endocervical epithelium was also positive in one case. Cases expressing Hep Par 1, with or without neuroendocrine coexpression, were associated with a higher rate of vascular invasion and a worse prognosis. Three of the five cases expressing neuroendocrine markers also coexpressed Hep Par 1.

CONCLUSIONS

Hep Par 1 expression in carcinoma of the cervix is not uncommon and is present in a variety of histological types. Expression of this marker appears to be associated with more aggressive biological behaviour and a worse prognosis. The uterine cervix is another site that may express Hep Par 1 and hence the use of this antibody in situations of diagnostic difficulty, especially involving lesions within the liver, have to be coupled with the knowledge of the range of tissues it may stain.

Hepatoid adenocarcinoma with liver metastasis mimicking hepatocellular carcinoma: an immunohistochemical and molecular study of eight cases

Hepatoid adenocarcinoma (HAC) is a special type of extrahepatic adenocarcinoma, which has a striking morphologic similarity to hepatocellular carcinoma. Seven HACs arising in the stomach and one in the lung, all with liver metastasis, were studied. They shared clinical features, such as old age, high serum alpha-fetoprotein level, aggressive behavior, and hepatic tumor in absence of risk factors for hepatocellular carcinoma (HCC). Morphologically, tumors were characterized by an admixture of tubulo-and/or papillary adenocarcinoma with hepatoid foci. In six cases, liver metastases showed an exclusive hepatoid differentiation, virtually indistinguishable from HCC with solid growth pattern. As HAC and HCC cannot be differentiated on the basis of morphology alone, differences in immunohistochemical reaction patterns would be of considerable diagnostic help. Immunostaining for CK7, CK8, CK18, CK19, CK20, alpha-fetoprotein, p-CEA, and HepPar1 revealed that hepatoid areas of both primary and metastatic HAC have a specific immunoprofile, distinctive of this entity. On the one hand, positivity of virtually all HACs for alpha-fetoprotein, CK8, CK18, and the membranous, canalicular staining for polyclonal carcinoembryonic antigen underline its hepatoid nature. On the other hand, positive staining for CK19 and CK20 and frequent negativity for HepPar1 in both primary tumors and their metastases were distinctive features of HAC. Furthermore, HAC differs from combined hepatocellular cholangiocarcinoma, being negative for CK7. In addition, for comparison of immunohistochemical results, we stained with the same antibody panel a tissue microarray of 121 HCCs. Comparative genomic hybridization study of three HAC supports their hepatoid differentiation as aberrations found in HAC are common in HCC (4q-, 8p-), and hepatoblastoma (Xq+), respectively.

Germ cell tumor-like neoplasms occurring outside the anatomic midline

Most germ cell tumors occur in the gonads or in extragonadal sites in the anatomic midline; this article reviews tumors with similar or identical histologic features that arise in other topographic locations. Such lesions often represent the presence of "germ cell-like" or "germinal" components in what is otherwise recognized as a somatic neoplasm; however, they may also occur in pure form. The morphologic and immunohistochemical features of these proliferations are reviewed, according to the types of germ cell tumors that they recapitulate.