OBJECTIVE: We evaluated the magnetic resonance imaging (MRI) features of ovarian teratomas with somatic-type malignancy (TSMs) and benign ovarian mature cystic teratomas (MCTs) to determine the diagnostic contribution of the MRI findings for differentiating these two teratomas.
METHODS: We compared the MRI findings between ovarian TSMs (n = 10) and MCTs (n = 193), and we conducted a receiver operating characteristic (ROC) analysis to determine the MRI findings\' contribution to the differentiation of TSMs from MCTs.
RESULTS: The maximum diameters of whole lesion and the largest solid component in the TSMs were larger than those of the MCTs (p = 0.0001 and p < 0.0001, respectively). Fat tissue in solid components was seen in 73/116 (62.9%) MCTs but in none of the TSMs (p = 0.0001). Ring-like enhancement in solid components was seen in 60/116 (51.7%) MCTs and none of the TSMs (p = 0.0031). On dynamic contrast-enhanced MRI (DCE MRI), all of the solid components in the TSMs showed a high- or intermediate-risk time intensity curve (TIC), and those in 113 of the 116 (97.4%) MCTs showed a low-risk TIC (p < 0.0001). The area under the curve of the ROC analysis using the high-/intermediate-risk TIC on DCE MRI was the highest (0.99) for differentiating TSMs from MCTs: sensitivity 100%, specificity 97.4%, positive predictive value 75.0%, negative predictive value 100%, and accuracy, 97.6%.
CONCLUSIONS: Compared to ovarian MCTs, ovarian TSMs are larger and have larger solid components with high- or intermediate-risk TICs on DCE MRI. Ovarian MCTs frequently show small solid components with fat tissue, ring-like enhancement, and a low-risk TIC on DCE MRI.

Somatic-type malignancy (STM) can occur infrequently within a primary or metastatic testicular germ cell tumor (TGCT) and is associated with dismal prognosis and survival. STM with chondrosarcomatous features is exceedingly rare and head and neck involvement has not been previously documented. A 39-year-old white man presented with nasal obstruction and epistaxis. Imaging disclosed a 6.9-cm expansile tumor involving the nasal cavity and skull base with intraorbital and intracranial extension. The histopathologic properties of the tumor were compatible with chondrosarcoma, grade II-III. Immunohistochemically, malignant cells were strongly and diffusely positive for S100 and epithelial markers, and showed loss of SMARCB1 expression. IDH1/2 mutations were not detected. Following whole-body PET scan, a 7.0-cm left testicular mass was discovered and diagnosed as seminoma with syncytiotrophoblastic cells, stage pT3NXM1b. Extensive retroperitoneal, mediastinal, and supraclavicular lymphadenopathy was also noticed. Histopathologic examination of the left supraclavicular lymph node revealed metastatic seminoma. By FISH, most metastatic nodal seminoma cells harbored 1 to 4 copies of isochromosome 12p, while the chondrosarcoma featured duplication of 12p. Presence of a malignant TGCT with disseminated supradiaphragmatic lymphadenopathy, the unique immunophenotypic properties of the skull-based chondrosarcoma and lack of IDH1/2 aberrations with gain of 12p strongly support the diagnosis of STM chondrosarcoma arising from metastatic TGCT. The patient did not respond to chemotherapy and succumbed three months after diagnosis. Although exceedingly uncommon, metastasis to the head and neck may occur in patients with TGCT. This case of STM chondrosarcoma demonstrated divergent immunophenotypic and molecular characteristics compared to \"typical\" examples of head and neck chondrosarcoma. High index of suspicion is advised regarding the diagnosis of lesions that present with otherwise typical histomorphology but unexpected immunohistochemical or molecular features.

In the post-chemotherapy setting, germ cell tumors of the testis (GCTT) that resemble non-specific sarcomas and co-express cytokeratins and glypican-3 (GPC3) are diagnosed as \"sarcomatoid yolk sac tumor postpubertal-type (YSTpt)\". The diagnosis of sarcomatoid YSTpt is clinically relevant but challenging due to its rarity, non-specific histology, and negative α-fetoprotein (AFP) staining. Recently, FOXA2 has emerged as a key-gene in the reprogramming of GCTT (activating the transcription of several genes, among which GATA3), and immunohistochemical studies showed that GATA3 and FOXA2 have a higher sensitivity for non-sarcomatoid YSTpt than GPC3 and AFP. We found that sarcomatoid YSTpt did not express FOXA2 [0: 14/14 (100%)] and showed focal expression of GATA3 [0: 12/14 (85.7%), 1 + : 2/14 (14.3%)], thus suggesting that these markers are not useful in diagnosing this tumor. Furthermore, we proposed a potential mechanism of sarcomatoid transformation in the post-chemotherapy setting of GCTT, mediated by the downregulation of FOXA2 and GATA3.

This article will review current aspects of the histopathological, immunohistochemical and molecular analysis of primary mediastinal germ cell tumours (PMGCTs) as well as their aetiological, epidemiological, clinical and therapeutic features. PMGCTs represent an important differential diagnosis in the spectrum of mediastinal tumours, and their diagnosis is usually made on small tissue samples from core needle biopsies in combination with diagnostic imaging and serum tumour markers. As in lymphomas, a small biopsy is often the only viable tumour sample available from these patients, as they receive chemotherapy prior to eventual surgical resection. Pathologists therefore need to apply an efficient combination of immunohistochemical markers to confirm the diagnosis of a PMGCT and to exclude morphological mimics.

We report the first known case of an adrenal teratoma containing a Wilms tumor component, in a 12-month-old girl with Trisomy 21. Despite adrenal teratomas being relatively uncommon, this particular instance raises interesting questions regarding the tumor origin, given the coexistence of both a teratoma and a Wilms tumor. Two main theories of development have been hypothesized, one of which suggests that the Wilms tumor may develop from a primary teratoma and the other proposing that the teratoma could originate from a primary Wilms tumor. Our case study leans toward the former, as the majority of the tumor displayed characteristics of a typical mature teratoma, with the Wilms component discovered as an incidental finding. Successful surgical intervention led to the gross total resection of the tumor. Twelve months post-resection, the patient remains free of recurrence. This report contributes to our understanding of these rare tumor types and underlines the importance of identifying the primary tumor to ensure appropriate management and treatment.

The development of somatic-type malignancy (SM) in testicular germ cell tumor represents a major challenge in the diagnosis and treatment of testicular cancer. Most SMs are derived from teratoma, and the remainder is associated with yolk sac tumor. They occur more frequently in metastases than in primary testicular tumors. SMs demonstrate a variety of histologic types, including sarcoma, carcinoma, embryonic-type neuroectodermal tumor, nephroblastoma-like tumor, and hematologic malignancy. Sarcoma, particularly rhabdomyosarcoma, accounts for the majority of SMs in the primary testicular tumors, whereas carcinoma, particularly adenocarcinoma, is the most common SM in metastases. Although SMs derived from testicular germ cell tumors mimic their histologic counterparts in other organs with overlapping immunohistochemical profiles, isochromosome 12p is present in most SMs, which can be useful in the differential diagnosis. The presence of SM in the primary testicular tumor may not worsen the outcome, but the development of SM in metastasis is associated with a poor prognosis. Furthermore, somatic-type carcinoma is likely associated with a worse prognosis than somatic-type sarcoma. Although SMs respond poorly to the cisplatin-based chemotherapy, timely surgical resection is an effective treatment for most patients.

A malignant germ cell tumor (GCT) might contain or transform into malignant non-germ cell histology, commonly referred to as somatic-type malignancy (SM). It is a rare phenomenon with poorly understood pathogenesis. SMs are mostly associated with teratomas and are mainly observed in late relapsing cases. There are no consensus guidelines on the management of SMs; however, surgery is considered to be the mainstay of treatment. Prognosis is variable depending on the time of diagnosis, site of relapse, and type of histology. Here, we present a case of a 44-year-old male with a history of mixed GCT stage IIA, initially managed with right radical orchiectomy, who developed a relapse of GCT 10 years later with an SM of adenocarcinoma subtype.

The development of somatic-type malignancy (SM) in testicular germ cell tumor represents a major challenge in the diagnosis and treatment of testicular cancer. Most SMs are derived from teratoma, and the remainder is associated with yolk sac tumor. They occur more frequently in metastases than in primary testicular tumors. SMs demonstrate a variety of histologic types, including sarcoma, carcinoma, embryonic-type neuroectodermal tumor, nephroblastoma-like tumor, and hematologic malignancy. Sarcoma, particularly rhabdomyosarcoma, accounts for the majority of SMs in the primary testicular tumors, whereas carcinoma, particularly adenocarcinoma, is the most common SM in metastases. Although SMs derived from testicular germ cell tumors mimic their histologic counterparts in other organs with overlapping immunohistochemical profiles, isochromosome 12p is present in most SMs, which can be useful in the differential diagnosis. The presence of SM in the primary testicular tumor may not worsen the outcome, but the development of SM in metastasis is associated with a poor prognosis. Furthermore, somatic-type carcinoma is likely associated with a worse prognosis than somatic-type sarcoma. Although SMs respond poorly to the cisplatin-based chemotherapy, timely surgical resection is an effective treatment for most patients.

Ovarian tumors include neoplasms derived from somatic cells and germ cells, including teratoma. Sometimes, tumors of the somatic cell type may develop from teratoma, causing diagnostic perturbation. We experienced a case of a tumor composed of several types of tissue in the ovary with a teratoma. When findings of teratoma and somatic tumor coexist in an ovary, it is difficult to differentiate whether a somatic tumor was mixed with a teratoma or a teratoma unitarily caused transformation to a somatic cell tumor. A 72-year-old Japanese woman (gravida, 3; para, 1) presented to our hospital with severe constipation and frequent urination, and a large intrapelvic tumor was detected by computed tomography (CT). Soon after admission, ultrasonography (US) and magnetic resonance imaging (MRI) revealed a large multilocular cystic tumor on her left ovary. Based on the clinical diagnosis of ovarian cancer, she underwent a left ovariectomy, appendectomy, and partial omentectomy. We observed an ovarian tumor consisting of teratoma, primitive neuroectodermal tumor (PNET), adenocarcinoma, various types of sarcomas, and clear cell carcinoma on the H and E-stained sections. The component of clear cell carcinoma showed a nuclear positive reaction against PAX8 and napsin A, as well as a loss of ARID1A, suggesting typical endometriosis-derived clear cell carcinoma. On the other hand, the expression of ARID1A was maintained in teratoma, PNET, non-specific adenocarcinoma, and various types of sarcomas, suggesting that these tumors had an origin different from that of clear cell carcinoma. These findings indicated that the ovarian tumor of this patient contained a clear cell carcinoma derived from a somatic cell and a teratoma that transformed to a wide variety of somatic cell types of tumors, which coexisted on one ovary. The appropriate use of immunohistochemistry was diagnostically effective in this case.

OBJECTIVE: Malignant germ cell tumours (GCTs) of the testis are rare neoplasms, but the most common solid malignancies in young men. World Health Organization guidelines divide GCTs into five types, for which numerous immunohistochemical markers allow exact histological subtyping in the majority of cases. In contrast, a germ cell origin is often hard to prove in metastatic GCTs that have developed so-called somatic malignant transformation. A high percentage, up to 89%, of GCTs are characterised by the appearance of isochromosome 12p [i(12p)]. Fluorescence in-situ hybridisation has been the most common diagnostic method for the detection of i(12p) so far, but has the disadvantages of being time-consuming, demanding, and not being a stand-alone method. The aim of the present study was to establish a quantitative real-time polymerase chain reaction assay as an independent method for detecting i(12p) and regional amplifications of the short arm of chromosome 12 by using DNA extracted from formalin-fixed paraffin-embedded tissue.
RESULTS: A cut-off value to distinguish between the presence and absence of i(12p) was established in a control set consisting of 36 tumour-free samples. In a training set of 149 GCT samples, i(12p) was detectable in 133 tumours (89%), but not in 16 tumours (11%). In a test set containing 27 primary and metastatic GCTs, all 16 tumours with metastatic spread and/or somatic malignant transformation were successfully identified by the detection of i(12p).
CONCLUSIONS: In summary, the qPCR assay presented here can help to identify, further characterise and assign a large proportion of histologically inconclusive malignancies to a GCT origin.