Giant bilateral prepubertal-type teratomas in a postpubertal patient: An illustrative case and review of the literature

Since the last World Health Organization (WHO) classification scheme for tumours of the urinary tract and male genital organs, there have been a number of advances in the understanding, classification, immunohistochemistry and genetics of testicular germ cell tumours. The updated 2016 draft classification was discussed at an International Society of Urological Pathology Consultation on Testicular and Penile Cancer. This review addresses the main updates to germ cell tumour classification. Major changes include a pathogenetically derived classification using germ cell neoplasia in situ (GCNIS) as a new name for the precursor lesion, and the distinction of prepubertal tumours (non-GCNIS-derived) from postpubertal-type tumours (GCNIS-derived), acknowledging the existence of rare benign prepubertal-type teratomas in the postpubertal testis. Spermatocytic tumour is adopted as a replacement for spermatocytic seminoma, to avoid potential confusion with the unrelated usual seminoma. The spectrum of trophoblastic tumours arising in the setting of testicular germ cell tumour continues to expand, to include epithelioid and placental site trophoblastic tumours analogous to those of the gynaecological tract. Currently, reporting of anaplasia (seminoma or spermatocytic tumour) or immaturity (teratoma) is not required, as these do not have demonstrable prognostic importance. In contrast, overgrowth of a teratomatous component (somatic-type malignancy) and sarcomatous change in spermatocytic tumour indicate more aggressive behaviour, and should be reported. Show more

The existence of a benign form of postpubertal testicular teratoma, apart from the rare dermoid cyst, is not widely recognized. This study reports 25 apparently benign postpubertal testicular teratomas, including 10 cases of dermoid cyst and 15 of nondermoid teratomas, which occurred in 25 patients, 12 to 59 years of age (mean, 24 y). Postpubertal status was based on active spermatogenesis in the testis. On gross examination 15 of 16 tumors with available information had a variably prominent cystic component filled with keratinous or mucoid material. On microscopic examination, the 10 dermoid cysts were lined by keratinizing, stratified squamous epithelium with associated pilosebaceous units and sweat glands in an organoid arrangement. Squamous cysts also occurred in 10 of 15 nondermoid teratomas, which by definition lacked adnexal structures. Apart from 2 dermoid cysts additional elements occurred in all cases, most commonly ciliated or respiratory-type epithelium (64%) and smooth muscle (68%). Organoid arrangements were also present in 5 of the nondermoid teratomas. No case showed cytologic atypia nor did the parenchyma adjacent to the teratomas of either type show intratubular germ cell neoplasia, unclassified type, microlithiasis, scarred zones, or more than focal perilesional tubular atrophy/sclerosis. Spermatogenesis was intact in all cases. FISH study for chromosome 12p was performed in 18 cases, and none displayed an abnormal 12p chromosome. All 17 patients that had follow-up information were alive at postoperative intervals of 5 to 168 months, although physician-confirmed disease-free status was unfortunately not available in 6 of these. This study supports the recognition and separate classification of not only dermoid cysts but also a small subset of apparently benign testicular teratomas in postpubertal patients that share many features with dermoid cysts but lack cutaneous-type adnexal structures. Features important in the recognition of both forms of these specialized teratomas of the postpubertal testis include absence of all of the following: cytologic atypia, intratubular germ cell neoplasia, unclassified type, significant tubular atrophy/tubular sclerosis, scarred zones, impaired spermatogenesis, microlithiasis, and evidence of chromosome 12p amplification. Other features include frequent organoid morphology and prominent components of ciliated epithelium and smooth muscle. It is important to distinguish these teratomas from the usual ones seen in postpuberal patients because of the malignant potential of the latter. Show more

Teratomas of the ovary and testis are confusing because, despite histologic similarities, they exhibit different biologic behaviors, depending mostly on the site of occurrence and the age of the patient. Thus, most ovarian teratomas are benign, and most testicular teratomas are malignant, with the exception of those occurring in children. These general statements, however, do not hold true for ovarian teratomas that are "immature" or exhibit "malignant transformation" and for dermoid and epidermoid cysts of the testis, categories of ovarian and testicular teratomas that are malignant and benign, respectively. This review concentrates on some of the "newer" observations concerning these interesting and confusing neoplasms, including diagnostically deceptive patterns. It is the author's opinion that much of the confusion regarding gonadal teratomas can be clarified by the concept that the usual ovarian teratoma derives from a benign germ cell in a parthenogenetic-like fashion, whereas the typical postpubertal testicular example derives from a malignant germ cell, mostly after evolution of that originally malignant cell to an invasive germ cell tumor (ie, embryonal carcinoma, yolk sac tumor, etc). The postpubertal testicular teratomas can therefore be thought of as an end-stage pattern of differentiation of a malignant germ cell tumor. The pediatric testicular teratomas, as well as dermoid and epidermoid cysts of the testis, however, must derive from benign germ cells, in a fashion similar to most ovarian teratomas. The teratomatous components of mixed germ cell tumors of the ovary, on the other hand, likely have a pathogenesis similar to that of postpubertal testicular teratomas. Show more