Immunohistochemical detection of p63 in testicular germ cell neoplasia

p63 expression in human tumors and normal tissues: a tissue microarray study on 10,200 tumors

Background

Tumor protein 63 (p63) is a transcription factor of the p53 gene family involved in differentiation of several tissues including squamous epithelium. p63 immunohistochemistry is broadly used for tumor classification but published data on its expression in cancer is conflicting.

Methods

To comprehensively catalogue p63 expression, tissue microarrays (TMAs) containing 12,620 tissue samples from 115 tumor entities and 76 normal tissue types were analyzed.

Results

p63 expression was seen in various normal tissues including squamous epithelium and urothelium. At least occasional weak p63 positivity could be detected in 61 (53%) of 115 different tumor types. The frequencies of p63 positivity was highest in squamous cell carcinomas irrespective of their origin (96–100%), thymic tumors (100%), urothelial carcinomas (81–100%), basal type tumors such as basal cell carcinomas (100%), and various salivary gland neoplasias (81–100%). As a rule, p63 was mostly expressed in cancers derived from p63 positive normal tissues and mostly not detectable in tumors derived from p63 negative cancers. However, exceptions from this rule occurred. A positive p63 immunostaining in cancers derived from p63 negative tissues was unrelated to aggressive phenotype in 422 pancreatic cancers, 160 endometrium cancers and 374 ovarian cancers and might be caused by aberrant squamous differentiation or represent stem cell properties. In 355 gastric cancers, aberrant p63 expression occurred in 4% and was linked to lymph node metastasis (p = 0.0208). Loss of p63 in urothelial carcinomas - derived from p63 positive urothelium - was significantly linked to advanced stage, high grade (p < 0.0001 each) and poor survival (p < 0.0001) and might reflect clinically relevant tumor dedifferentiation.

Conclusion

The high prevalence of p63 expression in specific tumor types makes p63 immunohistochemistry a suitable diagnostic tool. Loss of p63 expression might constitute a feature of aggressive cancers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40364-021-00260-5.

Extragonadal malignant teratoma in a dog - case report

ABSTRACT Teratomas are neoplasms thought to arise from germ cells which usually occur within gonads and are rarely described on extragonadal sites. The present study reports a case of a 15 year old female mongrel dog with a lumbosacral tumor. The tumor was microscopically composed of embryonic tissues with areas containing atypical undifferentiated cells, leading to the diagnosis of a malignant teratoma. Malignant teratomas are uncommon tumors in domestic animals.

Practical Applications in Immunohistochemistry: Carcinomas of Unknown Primary Site

CONTEXT

-Identification of the site of origin of carcinoma of unknown primary using immunohistochemistry is a frequent requirement of anatomic pathologists. Diagnostic accuracy is crucial, particularly in the current era of targeted therapies and smaller sample sizes.

OBJECTIVES

-To provide practical guidance and suggestions for classifying carcinoma of unknown primary using both proven and new antibodies, as well as targeting panels based on integration of morphologic and clinical features.

DATA SOURCES

-Literature review, the authors' practice experience, and authors' research.

CONCLUSIONS

-With well-performed and interpreted immunohistochemistry panels, anatomic pathologists can successfully identify the site of origin of carcinoma of unknown primary. It is crucial to understand not only the diagnostic uses of the many available antibodies but also the potential limits and pitfalls.

Clinicopathologic analysis of choriocarcinoma as a pure or predominant component of germ cell tumor of the testis

Although well recognized in the literature, the contemporary clinicopathologic data regarding choriocarcinoma (CC) as a pure or the predominant component of a testicular germ cell tumor (GCT) are limited. Herein, we present a series of pure CC and predominant CC in mixed GCT of the testis obtained from a single oncology institution. A comprehensive histologic review of 1010 orchiectomies from 1999 to 2011 yielded 6 (0.6%) pure CC and 9 (0.9%) mixed GCT cases with a predominant CC component. Patients' ages ranged from 20 to 39 years (median 29 y). All patients had markedly elevated serum β-hCG levels (median 199,000 IU/mL) at presentation. All tumors were unilateral and involved the right (9/15) and left (6/15) testis. The mean tumor size was 6.5 cm (range, 1.5 to 8 cm). Histology was similar for pure CCs and the CC component of mixed GCTs. CC commonly showed expansile hemorrhagic nodular cysts surrounded by variable layers of neoplastic trophoblastic cells (mononucleated trophoblasts and syncytiotrophoblasts). The syncytiotrophoblasts usually covered columns of mononucleated trophoblasts and occasionally formed plexiform aggregates and pseudovillous protrusions. Immunohistochemical stains suggested a mixture of cytotrophoblasts (p63+, HPL_) and intermediate trophoblasts (p63-, HPL weak +/-) in the columns of mononucleated cells. In the 9 mixed GCTs, CC comprised 50% to 95% (7/9 were ≥80% CC) of the tumor; 7 were combined with 1, and 2 were combined with 2 other GCT components. The non-CC components included teratoma (5/9), seminoma (2/9), yolk sac tumor (2/9), and embryonal carcinoma (2/9). Lymphovascular invasion, spermatic cord invasion, and tunica vaginalis invasion were present in 15/15, 5/15, and 1/12 cases, respectively. In mixed GCTs, these locally aggressive features were attributed to the CC component, except in 1 tumor in which it was also exhibited by the embryonal carcinoma component. Lymphovascular invasion was multifocal to widespread in 73% of tumors. The stages of the 15 tumors were: pT2 (10), pT3 (5); NX (1), N1 (4), N2 (5), N3 (5); and M1a (2) and M1b (13). Distant organ metastasis mostly involved the lungs (11) and liver (10). Follow-up information was available in 14 patients, all of whom received cisplatin-based chemotherapy. All 6 pure CC patients were dead of disease (range, 6 to 14 mo, median 9.5 mo). Follow-up of 8 patients with predominant CC (range, 10 to 72 mo, median 27 mo) showed that 5 died of the disease, and 1 was alive with disease and 2 were alive with no evidence of disease at 60 and 72 months of follow-up, respectively; these latter 2 patients were the only ones with M1a disease on presentation. This series confirms the proclivity for high-stage presentation including presence of distant metastasis, hematogenous spread, and poor outcome of testicular CC. Mixed GCT with a predominant CC component has similar tendency for high-stage presentation, marked elevation of serum β-hCG levels, and aggressive behavior compared with pure CC. This study also showed that distant metastasis by CC when only involving the lungs (M1a) may not be uniformly fatal with chemotherapy. The mononucleated trophoblastic columns in testicular CC appear to be a mixture of cytotrophoblasts and intermediate trophoblasts, similar to that described in gestational CC.