Both serum and tissue Galectin-1 levels are associated with adverse clinical features in neuroblastoma.

BACKGROUND: Neuroblastoma is one of the most common pediatric solid tumors. Although the 5-year overall survival rate has increased over the past few decades, high-risk patients still have a poor prognosis due to a lack of biomonitoring therapy. This study was performed to investigate the role of Galectin-1 in neuroblastoma biomonitoring therapy. PROCEDURE: A tissue microarray containing 37 neuroblastoma tissue samples was used to evaluate the correlation between Galectin-1 expression and clinical features. Blood samples were examined to better understand whether serum Galectin-1 (sGalectin-1) could be used for biomonitoring therapy. Kaplan-Meier analysis and ROC analysis was conducted to distinguish the outcome associated with high or low expression of Galectin-1 in patients with neuroblastoma. RESULTS: Increased Galectin-1 expression was found in neuroblastoma and it was further demonstrated that elevated tissue Galectin-1 expression was related to INSS stage, histology, bone marrow metastasis, and poor survival. sGalectin-1 levels were higher in newly diagnosed patients with neuroblastoma than healthy subjects. Patients with elevated sGalectin-1 through treatment cycles correlated with the poor chemo-responses and tended to have worse outcomes, such as metastasis or stable tumor size, whereas gradually decreasing sGalectin-1 levels correlated with no observed progression in clinical symptoms. CONCLUSIONS: Tissue and serum Galectin-1 levels were associated with adverse clinical features in patients with neuroblastoma, and sGalectin-1 could be a potential biomarker for monitoring therapy.

ZBTB16: a novel sensitive and specific biomarker for yolk sac tumor.

Although the function of zinc finger and BTB domain containing 16 (ZBTB16) in spermatogenesis is well documented, expression of ZBTB16 in germ cell tumors has not yet been studied. The aim of this study was to investigate the immunohistochemical expression and diagnostic utility of ZBTB16 in germ cell tumors. A total of 67 adult germ cell tumors were studied (62 testicular germ cell tumors, 2 ovarian yolk sac tumors, 1 mediastinal yolk sac tumor, and 2 retroperitoneal metastatic yolk sac tumors). The 62 testicular primary germ cell tumors are as follows: 34 pure germ cell tumors (20 seminomas, 8 embryonal carcinomas, 2 teratomas, 1 choriocarcinoma, 1 carcinoid, and 2 spermatocytic tumors) and 28 mixed germ cell tumors (composed of 13 embryonal carcinomas, 15 yolk sac tumors, 15 teratomas, 7 seminomas, and 3 choriocarcinomas in various combinations). Thirty-five cases contained germ cell neoplasia in situ. Yolk sac tumor was consistently reactive for ZBTB16. Among the 15 testicular yolk sac tumors in mixed germ cell tumors, all displayed moderate to diffuse ZBTB16 staining. ZBTB16 reactivity was present regardless of the histologic patterns of yolk sac tumor and ZBTB16 was able to pick up small foci of yolk sac tumor intermixed/embedded in other germ cell tumor subtype elements. Diffuse ZBTB16 immunoreactivity was also observed in 2/2 metastatic yolk sac tumors, 1/1 mediastinal yolk sac tumor, 2/2 ovarian yolk sac tumors, 2/2 spermatocytic tumors, 1/1 carcinoid, and the spermatogonial cells. All the other non-yolk sac germ cell tumors were nonreactive, including seminoma (n=27), embryonal carcinoma (n=21), teratoma (n=17), choriocarcinoma (n=4), and germ cell neoplasia in situ (n=35). The sensitivity and specificity of ZBTB16 in detecting yolk sac tumor among the germ cell tumors was 100% (20/20) and 96% (66/69), respectively. In conclusion, ZBTB16 is a highly sensitive and specific marker for yolk sac tumor.

[An Abnormal Alpha-Fetoprotein Fractionation Provides Additional Information: A Case of Retroperitoneal Germ Cell Tumor Accompanied by Liver Cirrhosis Type C].

Most of germ cell tumor is gonadal origin. However 5% of malignant germ cell tumors appear in extragonadal organs. Because extragonadal germ cell tumors (EGGCTs) are found anywhere on the midline such as pineal gland, mediastinum and retroperitoneum, the origin of this type of tumor is controversial. EGGCTs are often seen between childhood and young adult; an elderly patient with EGGCT is rarely met. Here we report a case that an abnormal alpha-fetoprotein (AFP) fractionation pattern was helpful for diagnosis of retroperitoneal germ cell tumor. A presenile man with hepatic cirrhosis caused by chronic hepatitis C showed an intraperitoneal tumor-like mass on computed tomography and thus hepatocellular carcinoma was suspected. A serological test re- vealed elevated total AFP level and AFP-L3%. The latter is the proportion of fucosylated AFP on the lectin-affinity based fractionation. Noticeably the fractionation pattern of AFP of this patient was abnormal, sug- gesting a diversity of lectin-affinity of AFP in germ cell tumors. This patient also showed an atypical in- crease in beta human chorionic gonadotropin (8hCG). We suggest the measurement of 6hCG for early differ- ential diagnosis of retroperitoneal germ cell tumor and hepatocellular carcinoma when an abnormal AFP frac- tionation pattern was detected in a patient with suspected hepatocellular carcinoma. [Short Communication].

SUCCESSFUL TREATMENT OF PULMONARY AND LYMPHATIC MANIFESTATIONS OF LYMPHANGIOLEIOMYOMATOSIS WITH SIROLIMUS.

Lymphangioleiomyomatosis (LAM) is a rare, progressive, diffuse cystic lung disease predominantly affecting women of child bearing age. Recently treatment with sirolimus was shown to stabilize lung function decline and improve quality of life in patients with LAM. We treated three premenopausal women suffering from LAM manifesting as diffuse cystic lung disease, chylous effusions, and lymphangioleioyomas with sirolimus (1-3 mg a day; sirolimus trough levels 2.9-8.5 ng/ml). All three patients had a remarkable response to sirolimus, with resolution of effusions, improvement in lung function and shrinking of abdominal lymphangioleiomyomas. Our case series further complements the literature in that sirolimus is a safe and effective treatment for LAM and its lymphatic manifestations.

Retroperitoneal liposarcoma with colonic involvement: a case report.

A 72-year-old male visited a local hospital on presentation of melena. Colonoscopy revealed a protruded lesion in the ascending colon, and computed tomography revealed a 20 cm retroperitoneal tumor. Biopsy failed to provide a definitive diagnosis of the colonic lesion. He was diagnosed as having a retroperitoneal liposarcoma and an ascending colon tumor using computed tomography, and referred to our hospital. Biopsy of the ascending colon lesion showed spindle cells with fibrosis. On immunohistochemical staining, tumor cells were positive for cyclin-dependent kinase 4 and murine double minute 2, and the lesion was diagnosed as a well-differentiated or dedifferentiated liposarcoma. The retroperitoneal liposarcoma, which had infiltrated the ascending colon, was resected along with the right colon and the right kidney. Macroscopically, the tumor had infiltrated the ascending colon, forming a multinodular solid mass in the lumen and the right kidney. Microscopic finding of the main tumor revealed a well-differentiated liposarcoma, and that of the colonic lesion revealed a dedifferentiated liposarcoma with nuclei of different sizes and shapes and increased spindle cell morphology. The right kidney and ureter were surrounded by tumor cells but were not infiltrated, and there was no lymph node involvement. The diagnosis of retroperitoneal liposarcoma is often difficult because symptoms appear only after the tumor becomes very large. Some retroperitoneal liposarcomas are found on computed tomography by chance. The clinical course of this case was very rare because of the presentation of melena as the first symptom and the detection of an invasive mass in the ascending colon using colonoscopy.

Angiomatoid fibrous histiocytoma: unusual sites and unusual morphology.

Angiomatoid fibrous histiocytoma is a soft tissue neoplasm of low malignant potential, typically occurring in the superficial soft tissues of the extremities in children and young adults. Occurrence outside somatic soft tissues is most uncommon. This report describes eight such cases, involving the lung (three cases), mediastinum (one case), vulva (two cases), retroperitoneum (one case) and ovary (one case), with the latter three locations being hitherto unreported sites of occurrence. Patients had a median age of 48 years, and presented with symptoms related to the mass lesion (five cases) or were incidentally found to harbor a tumor (three cases). Besides the typical histological features such as an outer shell of lymphoid tissue, multinodular aggregates of dendritic-like tumor cells, blood-filled spaces and abundant admixed plasma cells, unusual features were found focally in some cases, including clear cells, rhabdomyoblast-like cells, pulmonary edema-like pattern and tumor cell cords lying in a myxoid stroma. Immunoreactivity for the epithelial membrane antigen, desmin, smooth-muscle actin, CD68 and CD99 was found in 100, 63, 43, 100 and 100% of cases, respectively. Molecular studies provided support for the diagnosis in all seven tested cases-EWS gene translocation in six cases (partner gene being CREB1 in three and ATF1 in two in which information was available) and FUS gene translocation in one case. Comparison of the reported cases of extrasomatic angiomatoid fibrous histiocytoma with their somatic soft tissue counterparts showed a number of differences: higher mean age, slight male predominance (particularly for bone lesions), larger tumors, higher frequency of systemic symptoms, higher recurrence rate, myxoid change being more common and a much higher frequency of EWS/ATF1 gene fusion.

[Solitary fibrous tumor of the abdomen. A rare neoplasm of vascular origin]. / Tumor fibroso solitario abdominal. Una rara neoplasia de origen vascular.

Solitary fibrous tumor (formerly known as hemangiopericytoma) is a rare soft tissue neoplasm, most frequently arising from the retroperitoneum and lower extremities. We present two cases of retroperitoneal solitary fibrous tumors diagnosed after surgical removal. We provide a literature review showing the basic clinical, pathologic and therapeutic features of these tumors.

Primary retroperitoneal myxoid/round cell liposarcoma is a nonexisting disease: an immunohistochemical and molecular biological analysis.

Almost all primary retroperitoneal liposarcomas can be classified as well-/dedifferentiated liposarcoma. Rarely, however, primary retroperitoneal liposarcoma is classified as myxoid/round cell liposarcoma, based on the presence of myxoid areas and vascular crow's feet pattern, which has resulted in a debate on the classification of liposarcoma in the retroperitoneum. Genetically, myxoid/round cell liposarcoma and well-/dedifferentiated liposarcoma are different diseases. Myxoid/round cell liposarcoma is characterized by a translocation causing FUS-CHOP or EWSR1-CHOP fusion, whereas well-/dedifferentiated liposarcoma is characterized by an amplification of the 12q13-15 region, including MDM2 and CDK4 genes. As myxoid/round cell liposarcoma is highly radio- and chemosensitive, differentiation between subtypes is important to optimize treatment. We studied whether primary retroperitoneal liposarcomas diagnosed as myxoid/round cell liposarcoma represent molecularly true myxoid/round cell liposarcoma or are histopathological mimics and represent well-/dedifferentiated liposarcoma. Primary retroperitoneal myxoid/round cell liposarcoma (n=16) were compared to primary extremity myxoid/round cell liposarcoma (n=20). Histopathological and immunohistochemical features were studied. Amplification status of the 12q13-15 region was studied using a multiplex ligation-dependent probe amplification analysis, and FUS-CHOP or EWS-CHOP translocations were studied using RT-PCR. In primary retroperitoneal myxoid/round cell liposarcoma, MDM2 and CDK4 staining was both positive in 12 of 15 cases. In primary extremity myxoid/round cell liposarcoma, MDM2 was negative in 18/20 and CDK4 was negative in all cases. Multiplex ligation-dependent probe amplification showed the amplification of 12q13-15 region in 16/16 primary retroperitoneal myxoid/round cell liposarcomas and in 1/20 primary extremity myxoid/round cell liposarcomas. Translocation was present in all (18/18) primary extremity myxoid/round cell liposarcomas, but absent in all primary retroperitoneal myxoid/round cell liposarcomas. On the basis of immunohistochemical and molecular characteristics, apparent primary retroperitoneal myxoid/round cell liposarcoma can be recognized as well-/dedifferentiated liposarcoma with morphological features mimicking myxoid/round cell liposarcoma. In these cases, treatment should probably be specifically designed as for well-/dedifferentiated liposarcoma. Moreover, finding of myxoid/round cell liposarcoma translocations in a retroperitoneal localization is highly suggestive of metastasis and should prompt search for a primary localization outside the retroperitoneum.

Sclerosing PEComa: clinicopathologic analysis of a distinctive variant with a predilection for the retroperitoneum.

PEComas (tumors showing perivascular epithelioid cell differentiation) are a family of mesenchymal neoplasms that include angiomyolipoma, clear cell "sugar" tumor of the lung, lymphangiomyomatosis, and a group of uncommon lesions that arise in soft tissue, visceral organs, and skin. We describe a distinctive variant of PEComa that shows extensive stromal hyalinization, a feature not previously described in these tumors. Thirteen PEComas with extensive stromal hyalinization were identified from a total of 70 cases of PEComa received between 1996 and 2006 (19%). All patients were women, with a mean age of 49 years (range, 34 to 73y). One patient had tuberous sclerosis. Ten tumors (77%) arose in the retroperitoneum (8 pararenal), and 1 each in the pelvis, uterus, and abdominal wall. Median tumor size was 9.5 cm (range, 4.5 to 28 cm). All except 2 were grossly well-circumscribed. The tumors were composed of cords and trabeculae of cytologically uniform bland epithelioid cells with palely eosinophilic, granular to clear cytoplasm and round nuclei with small nucleoli, embedded in abundant densely sclerotic stroma. Five tumors contained a spindle cell component, and 6 showed focally sheetlike areas. In all cases the tumor cells were focally arranged around blood vessels. All tumors lacked the delicate nesting vascular pattern typical of other PEComas. Mitoses ranged from 0 to 3/50 high-power field (mean 1) in all cases except 1. One tumor showed abrupt transition to areas with strikingly pleomorphic morphology, marked nuclear atypia, frequent mitoses (22/10 high-power field), and fascicular and nested architecture. This was the only case with necrosis. All tumors were immunopositive for desmin (usually diffusely) and HMB-45 (generally in scattered cells); 12/13 (92%) expressed smooth muscle actin, 11/12 (92%) caldesmon, 11/12 (92%) microphthalmia transcription factor (D5), and 3/13 (23%) melan-A. Only 1 (8%) was focally S-100 positive. All tumors were negative for epithelial membrane antigen, PAN-K, and KIT (CD117). Follow-up was available for 9 patients, ranging from 10 to 64 months (median, 33). One patient (whose tumor showed transition to high-grade malignant morphology) developed metastases to lung, liver, and abdominal wall. No other tumor has recurred or metastasized thus far. Sclerosing PEComa is a distinctive variant with a predilection for the pararenal retroperitoneum of middle-aged women. Sclerosing PEComas seem to pursue an indolent clinical course, unless associated with a frankly malignant component. Long-term follow-up will be required to confirm these findings.

Sclerosing variant of epithelioid angiomyolipoma.

Presented herein are two unusual epithelioid angiomyolipomas (AML) displaying prominent stromal sclerosis. Both patients were middle-aged women without a clinical history of tuberous sclerosis. One patient (case 1) had a 2 cm lesion arising in the renal cortex, and another (case 2) had a pararenal retroperitoneal tumor measuring 13 cm. Both tumors were composed of sheets or nests of polygonal epithelioid or short spindle cells having uniform round to oval nuclei and eosinophilic cytoplasm with cords of hyalinized sclerotic stroma between them. The tumor in case 2 had small areas of mature-looking fat cells. Immunohistochemically, epithelioid tumor cells were diffusely positive for actins and desmin in both cases, and melanoma antigen recognized by T cells (MART)-1 was positive in patient 2. Scattered HMB-45-immunoreactive cells were identified in the sclerotic cords of both tumors, but epithelioid tumor cells were essentially negative for HMB-45. The characteristic clinicopathological and immunohistochemical features of the present cases are analogous to a subset of epithelioid AML or sclerosing perivascular epithelioid cell tumors previously reported.

Lipomatous ganglioneuroma of the retroperitoneum.

A unique case of ganglioneuroma mimicking a lipomatous tumor in a 73-year-old man is reported. The tumor was incidentally found on radiography performed for unrelated reasons. Because of the fat element, CT and magnetic resonance imaging suggested myelolipoma inside or outside the right adrenal gland. The laparotomy indicated that the tumor was located on the right adrenal gland. It was well circumscribed but not encapsulated, and was approximately 2 cm in diameter. Microscopically, ganglioneuromatous component was scattered in the background of a large amount of adipose tissue. Because the presence of such a large amount of adipose tissue seems to be rare in ganglioneuromas, its histogenesis is discussed.

Colonic-type adenocarcinoma arising in a primary retroperitoneal mature cystic teratoma.

A 47-year-old woman who presented with abdominal pain was found to have a 20 cm cystic retroperitoneal mass. Pathology indicated a colonic-type adenocarcinoma arising in a primary retroperitoneal mature cystic teratoma. The adenocarcinoma was predominantly intracystic with focal superficial invasion into the cyst wall but not beyond the teratoma capsule. Immunohistochemistry showed that the adenocarcinoma cells were diffusely positive for cytokeratin 20 (CK20) and caudal-type homeobox transcription factor-2 (CDX2) but negative for CK7, confirming the colonic phenotype. In addition, the adenocarcinoma was seen adjacent to teratomatous colonic-type mucosa with adenomatous change (i.e. adenoma), suggesting that it was probably arising from a colonic-type adenoma within the teratoma. The carcinoma had a higher Ki-67 proliferation index and had a higher percentage of cells stained for p53 than the adjacent adenomatous lesion. To the authors' knowledge this is the first documented case in which a colonic-type adenocarcinoma was seen arising from a precursor lesion (i.e. a colonic-type adenoma in a primary retroperitoneal mature cystic teratoma) and is the second case of intestinal-type adenocarcinoma arising in a primary retroperitoneal mature cystic teratoma.

Dedifferentiated liposarcomas with divergent myosarcomatous differentiation developed in the internal trunk: a study of 27 cases and comparison to conventional dedifferentiated liposarcomas and leiomyosarcomas.

Dedifferentiated liposarcoma (DLPS) is one of the most frequent sarcomas of the retroperitoneum and represents most undifferentiated sarcomas of the internal trunk. In about 5% cases, the dedifferentiated component is an heterologous sarcoma such as leiomyosarcoma or rhabdomyosarcoma. We reviewed a series of 65 sarcomas with a myogenic differentiation developed in the internal trunk for which initial diagnoses were leiomyosarcoma (37), rhabdomyosarcoma (6), malignant mesenchymoma (6), and DLPS (16). Immunostainings for MDM2, CDK4, alpha smooth actin, desmin, caldesmon, myogenin, c-kit, and progesterone receptor were performed. In 48 cases, the amplification status of MDM2 and CDK4 could be evaluated with quantitative polymerase chain reaction on paraffin-embedded tissues extracted DNAs. After review of the cases, final diagnoses were leiomyosarcoma (35), rhabdomyosarcomatous (20) or leiomyosarcomatous (7) DLPS, probable DLPS (2), and malignant mesenchymoma (1). DLPS were bigger tumors (median: 18.2 cm) than leiomyosarcomas (median: 12 cm). They had a lower 5-year recurrence-free survival than leiomyosarcomas (45% vs. 71%) but a higher 5-year metastasis-free survival (73% vs. 39%). There was no significant difference in overall survival (57% vs. 34%). Outcome of patients with a DLPS with a myosarcomatous component did not differ from conventional DLPS. In conclusion, most sarcomas with a rhabdomyosarcomatous differentiation occurring in the internal trunk of adults are DLPS. Moreover, DLPS with a myogenic component have a low metastatic potential, similar to conventional DLPS and significantly lower to the metastatic potential of leiomyosarcomas.

Germ cell tumors with sarcomatous components: a clinicopathologic and immunohistochemical study of 46 cases.

The clinicopathologic features of 46 patients with germ cell tumors with sarcomatous components (GCTSC) involving either the primary site or their metastases were studied. There were 43 men and 3 women aged 17 to 74 years. Twenty-three tumors arose in the mediastinum, 2 in the retroperitoneum, and 21 in the gonads. The germ cell component consisted of pure mature or immature teratoma (23 cases), teratoma mixed with other seminomatous or nonseminomatous components (17), pure seminoma (2), intratubular germ cell neoplasia (1), and yolk sac tumor (1). The SC included embryonal rhabdomyosarcoma (29), angiosarcoma (6), leiomyosarcoma (4), undifferentiated sarcoma (3), myxoid liposarcoma (1), malignant peripheral nerve sheath tumor (1), malignant "triton" tumor (1), and epithelioid hemangioendothelioma (1). Immunohistochemical studies were carried out in 34 cases with appropriate results supporting the diagnoses. Metastases containing both GCT and SC were observed in 6 cases, metastases of SC alone in 4, and metastases containing only GCT elements in 3. All patients were treated by cisplatinum-based chemotherapy plus other agents followed by surgery. Clinical follow-up was available in 40 patients (1 to 96 mo; mean=24 mo). Thirty-two of 40 patients either died of tumor (25/40; 62.5%) or were alive with advanced, progressive disease (7/40; 17.5%), and only 8/40 (20%) were alive and free of disease between 5 to 40 months (mean=18 mo). Comparison of these patients with an age-matched and stage-matched control group of patients with GCT without SC showed statistically significant differences in survival between the 2 cohorts (P

Retroperitoneal schwannomas: diagnostic and therapeutic implications.

AIMS AND BACKGROUND: Schwannomas are a rare group of soft-tissue tumors that are derived from the peripheral nerve sheath and rarely develop in the retroperitoneum. METHODS AND STUDY DESIGN: We reviewed the clinicopathological features of 4 patients referred to our unit between October 1999 and March 2004 who on radiological examination were diagnosed with pancreatic, adrenal, psoas and retroperitoneal fat tissue tumors and subsequently underwent surgical treatment. RESULTS: The preoperative diagnosis was incorrect in all cases. At time of surgery, we found a mass probably arising from the adrenal gland in 2 patients, a lesion originating from the femoral nerve in 1 patient, and a retroperitoneal mass without a clear site of origin in 1 patient. Pathological evaluation revealed schwannomas in all cases, with no signs of malignancy. Complete surgical excision was performed in all patients without any major postoperative complications. At the time of writing all patients are alive with no evidence of local or distant recurrence. CONCLUSIONS: Radical surgical excision is considered the best treatment for these neoplasms, resulting in a very good longterm prognosis.

GIST Manifesting as a Retroperitoneal Tumor: Clinicopathologic Immunohistochemical, and Molecular Genetic Study of 112 Cases.

Most gastrointestinal stromal tumors (GISTs) occur in the tubular gastrointestinal (GI) tract, but some present apparently outside the GI tract. In this study, we analyzed 112 GISTs located in the retroperitoneum. These tumors occurred in 55 women and 57 men with a median age of 65 years (range: 21 to 89 y). On the basis of clinically or histologically detected connections to GI tract, 15 tumors were considered likely of gastric, 9 duodenal, and 13 of small intestinal origin. The remaining cases were categorized by location as peripancreatic (n=25), pelvic (n=11), mesenteric (n=4), and of unspecified/miscellaneous sites (n=35). The tumors varied in size 3 to 35 cm (median, 15 cm) and by mitotic rate per 5 mm, 0 to >100 (median, 10). Histologically the tumors apparently arising outside the GI tract had features of intestinal (n=41) and gastric GISTs (n=25); 9 cases had indeterminate histology. The histologic variants included spindled, epithelioid, vacuolated, nested, and myxoid potentially simulating other tumors such as liposarcoma and solitary fibrous tumor. Most GISTs were KIT-positive (106/112 cases), and the remaining 6 tumors were DOG1/Ano1-positive. Five cases showed focal nuclear positivity for MDM2. KIT mutations were detected in 42/59 cases, and PDGFRA mutations in 4/16 KIT wild-type and 3/5 of the KIT-negative tumors analyzed. One pelvic retroperitoneal GIST was succinate dehydrogenase deficient. All 79 patients were dead at last follow-up with a median survival of 14 months, with few survivals >5 years. Only operable versus inoperable tumor was a statistically favorable factor in univariate analysis (P<0.01). In multivariate analysis, mitotic rate >50/5 mm was significant for a shorter survival (hazard ratio, 5.25; 95% confidence interval, 1.65-16.8; P<0.01). Histologic and clinicopathologic similarity of extragastrointestinal retroperitoneal GISTs with GISTs of GI tract suggests their GI tract origin. Potentially overlapping features between GIST and other retroperitoneal tumors necessitate use of multiple diagnostic markers and molecular genetic studies.

Giant intra-abdominal mature cystic teratoma (dermoid cyst) in an adult man, with male genitourinary tissue including prostatic and penile elements.

We describe a case of a giant intra-abdominal mature cystic teratoma in a 36-year-old man, which comprised typical features of differentiated teratoma/dermoid cyst but which contained a macroscopic rudimentary penis, with vasoformative erectile tissue-like structures consistent with corpora cavernosa, as well as scrotal-type skin and prostatic tissue. The genitourinary structures were well formed both grossly and microscopically and sharply demarcated from the rest of the neoplasm, which comprised typical differentiated teratoma, without any other macroscopic foci of organoid differentiation or of other histologic differentiation. The plasticity of the cells of differentiated teratoma, which enables it to undergo multidirectional differentiation, is well recognized, but the factors determining this distinct path of differentiation remain to be established.