Search

The majority of penile malignant tumors are squamous cell carcinomas. They are pathologically defined as epithelial neoplasms originating in the squamous cells of the inner mucosal lining of the glans, coronal sulcus or foreskin. Tumor location and site of origin is preferentially in glans (70%) followed by foreskin (25%) and coronal sulcus (5%). Despite the variable geographic distribution, pathological features of penile carcinomas in areas of high- and low-risk are similar. Penile tumors are morphologically heterogeneous. A major advance, based on biological, etiological and prognostic factors, is the 2016 WHO classification separating epithelial penile neoplasia, precancerous and invasive, in non-HPV and HPV-related.

There are few pathologic or molecular studies of penile precancerous lesions, and the majority refers to lesions associated with invasive carcinomas. Penile Intraepithelial Neoplasia (PeIN) is classified in two morphologically and distinctive molecular groups, non-HPV and HPV-related with special subtypes. The primary purpose of this international series was to classify PeIN morphologically, detect HPV genotypes and determine their distribution according to PeIN subtypes. A secondary aim was to evaluate the p16

ZusammenfassungDas zunehmende Verständnis molekularer Grundlagen von Tumoren sowie der Fortschritt in der Diversifizierung der onkologischen Therapien versprechen individualisierte Therapieoptionen, welche bislang jedoch nur ansatzweise in die Therapieplanung von urologischen Tumoren eingegangen sind. Daher hat die Internationale Gesellschaft für Urologische Pathologie (ISUP) im März 2019 eine Konsenskonferenz zur Erarbeitung evidenzbasierter Handlungsempfehlungen zur molekularpathologischen Diagnostik beim Urothelkarzinom, Nierenzellkarzinom, Prostatakarzinom, Peniskarzinom und testikulären Keimzelltumoren durchgeführt. Die auf dieser Konsenskonferenz erarbeiteten Empfehlungen sind kürzlich in 5 separaten Manuskripten veröffentlich worden und werden in der vorliegenden Arbeit zusammengefasst.Im Rahmen der Konferenzvorbereitung wurde eine umfassende Umfrage zur derzeitigen Praxis molekularer Testungen bei urogenitalen Tumoren unter den Mitgliedern der ISUP durchgeführt. Auf der Konferenz wurden die Ergebnisse und die entsprechenden Hintergrundinformationen durch 5 Arbeitsgruppen präsentiert und Handlungsempfehlungen für die Diagnostik erarbeitet. Eine Übereinstimmung von 66 % der Konferenzteilnehmer wurde als Konsens definiert.

Penile cancer and its precursor lesions are morphologically and clinically heterogenous and they can be further characterized by immunohistochemical (IHC) and molecular genetic analyses. According to the current World Health Organization (WHO) classification, penile intraepithelial neoplasia (PeIN) and invasive penile carcinomas can be grouped into human papillomavirus (HPV)-related and non-HPV-related neoplasms. This distinction is clinically relevant for etiological and prognostic reasons. To gain insight into the current use of molecular testing and IHC in their diagnostics, a survey was held among the membership of the International Society of Urological Pathology (ISUP). About 250 pathologists from 51 countries answered the survey on the practice and use of IHC/molecular technique as aids in the diagnosis of penile squamous neoplasia. More than half (60%) of the respondents worked at an academic hospital. The questions focused on condylomas, precancerous squamous lesions, and squamous cell carcinoma (SCC). About 35% to 45% of the pathologists considered the use of IHC or molecular tests of value in the pathologic evaluation of precancerous and invasive neoplasms. The vast majority of the respondents do not use IHC for the diagnosis and subtyping of condylomas. There is emerging evidence that some condylomas may participate in the penile carcinogenesis process, especially the high-risk HPV-related atypical condylomas. We recommend the use of p16 in such cases. For most PeIN cases, about half of the responding pathologists make the diagnosis on hematoxylin and eosin slides only. For their subtyping, 50% to 55% of the pathologists use IHC in warty or basaloid PeINs and 40% in differentiated PeIN. To separate HPV-related PeIN from non-HPV-related PeIN, 80% reported using p16 and 20% Ki-67. On the basis of literature review and our practice, the ISUP working group recommends the use of Ki-67 to separate non-HPV-differentiated PeIN from squamous hyperplasia and the use of p16 to distinguish the pleomorphic variant of differentiated PeIN from HPV-related PeIN. With respect to SCCs, according to the survey, immunostaining is only applied in 15% of conventional invasive SCCs, the majority being diagnosed by hematoxylin and eosin. To separate HPV and non-HPV tumors, most (80%) would use p16 and 25% would use p53. For subtype classification, they consider IHC necessary to identify verrucous, papillary, warty, warty-basaloid, and basaloid carcinomas. p16 is used as a surrogate of polymerase chain reaction for the identification of high-risk HPV. We recommend the use of p16 immunostain in cases where the tumoral histologic features of the SCCs are not classical for HPV-related neoplasms, especially in poorly differentiated tumors. Because the majority of these neoplasms harbor high-risk HPV (HPV16), identifying the presence of the virus is rather more important than documenting its specific genotype.

Penile intraepithelial neoplasia (PeIN) is currently classified in human papillomavirus (HPV)- and non-HPV-related subtypes with variable HPV genotypes. PeINs are frequently associated with other intraepithelial lesions in the same specimen. The aim of this study was to detect and compare HPV genotypes in PeINs and associated lesions using high-precision laser capture microdissection-polymerase chain reaction and p16INK4aimmunostaining. We evaluated resected penile specimens from 8 patients and identified 33 PeINs and 54 associated lesions. The most common subtype was warty PeIN, followed by warty-basaloid and basaloid PeIN. Associated lesions were classical condylomas (17 cases), atypical classical condylomas (2 cases), flat condylomas (9 cases), atypical flat condylomas (6 cases), flat lesions with mild atypia (12 cases), and squamous hyperplasia (8 cases). After a comparison, identical HPV genotypes were found in PeIN and associated lesions in the majority of the patients (7 of 8 patients). HPV16 was the most common genotype present in both PeIN and corresponding associated lesion (50% of the patients). Nonspecific flat lesions with mild atypia, classical condylomas, and atypical condylomas were the type of associated lesions most commonly related to HPV16. Other high-risk HPV genotypes present in PeIN and associated nonspecific flat lesion with mild atypia were HPV35 and HPV39. In this study of HPV in the microenvironment of penile precancerous lesions, we identified identical high-risk HPV genotypes in PeIN and classical, flat, or atypical condylomas and, specially, in nonspecific flat lesions with mild atypia. It is possible that some of these lesions represent hitherto unrecognized precancerous lesions.

Penile cancer is an under-studied disease that occurs more commonly in developing countries and 30-50% of cases show high-risk human papillomavirus (HPV) infection. Therapeutic advances are slow, largely due to the absence of animal models for translational research. Here, we report the first mouse model for HPV-related penile cancer. Ten-week-old mice expressing all the HPV16 early genes under control of the cytokeratin 14 (Krt14) gene promoter and matched wild-type controls were exposed topically to dimethylbenz(a)anthracene (DMBA) or vehicle for 16 weeks. At 30 weeks of age, mice were sacrificed for histological analysis. Expression of Ki67, cytokeratin 14, and of the HPV16 oncogenes E6 and E7 was confirmed using immunohistochemistry and quantitative PCR, respectively. HPV16-transgenic mice developed intraepithelial lesions including condylomas and penile intraepithelial neoplasia (PeIN). Lesions expressed cytokeratin 14 and the HPV16 oncogenes E6 and E7 and showed deregulated cell proliferation, demonstrated by Ki67-positive supra-basal cells. HPV16-transgenic mice exposed to DMBA showed increased PeIN incidence and squamous cell carcinoma. Malignant lesions showed varied histological features closely resembling those of HPV-associated human penile cancers. Wild-type mice showed no malignant or pre-malignant lesions even when exposed to DMBA. These observations provide the first experimental evidence to support the etiological role of HPV16 in penile carcinogenesis. Importantly, this is the first mouse model to recapitulate key steps of HPV-related penile carcinogenesis and to reproduce morphological and molecular features of human penile cancer, providing a unique in vivo tool for studying its biology and advancing basic and translational research. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Since the seminal study of Hart and Helwig in 1975, there are few detailed pathological studies of lichen sclerosus (LS). The aims of this study were to provide a detailed histopathological description of penile LS, as well as to explore its relationship with penile intraepithelial neoplasia (PeIN) or invasive carcinoma. We evaluated 200 patients and designed a topographical approach for the histological evaluation focusing in alterations of the following anatomical layers: squamous epithelium, lamina propria, dartos, and corpus spongiosum. We documented the quantity and topographical location of stromal lymphocytes. The prevalent lesions found were epithelial hyperplasia, atrophy, PeIN, basal cell vacuolization, lamina propria sclerosis, and variable patterns of lymphocytic infiltration. Various unique patterns of stromal sclerosis were described: perivascular, globular, linear, and solid fibrosis/hyalinization; any of them were found to be diagnostic for LS. The variation in the topography and density of lymphocytes was determinant for the identification of LS morphological variants: lichenoid, band-like, lymphocytic depleted, and mixed. A major finding was the identification of the variant designated as lymphocytic depleted LS, which we considered as the morphological prototype of LS associated with penile neoplasia. The detailed description of this complex lesion presented in this study may help pathologists in practice to identify and better define LS. The identification of the special variants suggests a role of the stromal lymphocytes in the process of carcinogenesis. Confirmation of the observations with more studies is necessary to determine the significance of these findings.

Since 1995 it has been known that tumors harboring human papillomavirus (HPV) preferentially show basaloid or condylomatous histological features, while HPV-negative tumors have a different morphology. New classification models separate subtypes of penile squamous cell carcinomas in two groups, non-HPV- and HPV-related. It is purported that HPV-related tumors have better prognosis. Other features such as inflammatory cell-rich medullary, clear-cell, and lymphoepithelioma-like patterns are also strong predictors of the presence of HPV. These tumors are morphologically distinctive and with some experience, pathologists may recognize them after routine hematoxylin and eosin staining. Occasionally, p16 immunostaining may aid in differential diagnosis. The gold standard for HPV detection is polymerase chain reaction, but this technique is expensive and not available in most pathology laboratories. In situ hybridization is useful and p16 immunostaining can detect HPV in approximately 85% of cases. There is correlation between morphology and outcome. PATIENT SUMMARY: This mini review provides an overview of the latest classification for penile invasive carcinoma and penile intraepithelial neoplasia.

Lichen sclerosus (LSc) with penile cancer is found in about two thirds of specimens. It has been hypothesized that LSc represents a precancerous condition. To qualify as such, in addition to cytological atypia and similarity with the invasive tumor, a spatial correlation between LSc and neoplastic lesions needs to be demonstrated. The purpose of this study was to evaluate such a spatial relationship. Circumcision (28 cases) and penectomy (81 cases) specimens were evaluated. All cases had LSc, penile intraepithelial neoplasia (PeIN), and/or invasive squamous cell carcinomas. We examined LSc in relation to invasive carcinoma, PeIN, and normal epithelia. Invasive squamous cell carcinomas, classified according to the World Health Organization criteria as non–human papillomavirus (HPV)-related and HPV-related PeIN, were present in 100 cases. Non-HPV-related (differentiated) PeIN was the most common subtype associated with LSc (89%). There were 5 spatial patterns identified: (1) LSc adjacent to PeIN (23%), (2) LSc adjacent and comprising PeIN (42%), (3) LSc next to and within invasive carcinomas (8%), (4) LSc throughout the sequence PeIN-invasive carcinoma (24%), and (5) LSc was separate (with normal tissue between the lesions) from PeIN and/or invasive carcinomas in a minority of cases (3%). LSc within the cancer was not previously described. In this series, we found 35 cases with LSc within invasive carcinomas. The striking continuous spatial relationship among LSc, PeIN, and/or invasive carcinoma as shown in this study may be a necessary (but not sufficient) condition for the hypothesis postulating LSc as a penile precancerous lesion.

Adipose tissue, along with arteries, veins, and peripheral nerves, is a normal constituent of mesenchymal tissues encasing the corpora cavernosa at the level of the penile shaft, variously designated as penile fascia or Bucks fascia. To our knowledge, the presence of fat has not been previously reported within the corpora cavernosa. One or 2 transversal histologic sections at the level of the surgical margin at the shaft of 63 consecutive partial penectomy specimens for squamous cell carcinoma were evaluated. From outer to inner tissues, 3 anatomic levels were identified: (1) outer fascia composed of a loose fibrovascular mesenchyme containing some nerve branches. Adipose tissue was present in the majority of the cases. (2) The tunica albuginea, a thick and dense fibroelastic band of tissue separating the outer fascia from the erectile tissues of the corpora cavernosa. Adipose tissue within the albuginea was present in 21 specimens (19%). (3) Erectile tissues of corpora cavernosa. Besides the typical erectile tissues, adipose tissue was present in 33 cases (52%). The fatty tissue was focal or multifocal and scant and peripherally located at the junction of the tunica albuginea with the corpora. In some cases, it was associated with small amounts of fibrous tissue, small vessels, and nerves. We are reporting the presence of adipose tissue in the tunica albuginea and the corpora cavernosa. It is possible that adipose tissue, along with small nutritional vessels and nerves perforates from the fascia, in which fat is usually present, through the tunica albuginea to reach the corpora. In a previous examination of the local routes of cancer spread, we found this pathway to be one of the mechanisms of cancer invading the penile corpora from the penile fascia.

A third to half of penile invasive squamous cell carcinomas are human papillomavirus (HPV) related. Warty (condylomatous), warty-basaloid, and basaloid carcinomas are the most common subtypes associated with HPV. Less frequent are clear cell and lymphoepithelioma-like carcinomas. Here we report a novel penile tumor associated with HPV. Twelve cases were selected from 1010 penile carcinomas, part of an international HPV detection study conducted at the Institut Catala d'Oncologia, Barcelona, Spain. Immunostaining with p16 was performed on all cases, and HPV-mRNA detection was also performed. En bloc full tumor staining was the utilized criteria for positivity of p16. For HPV-DNA detection, whole-tissue section polymerase chain reaction analysis was performed by SPF10-DEIA-LiPA25 (version 1). The patients' ages ranged from 42 to 92 years (average, 71 y). The tumor was most commonly located in the glans. A characteristic microscopic finding was the presence of a moderate to dense tumor-associated inflammatory cell infiltrate composed of neutrophils, lymphocytes, plasma cells, or eosinophils. Tumors grew in large solid sheets, nests, or had a trabecular pattern. Cells were large and poorly differentiated or anaplastic. Keratinization was minimal or absent. Nuclei were large with prominent nucleoli. Mitoses were numerous. Tumor necrosis was common. Deep invasion of the corpora cavernosa was frequent. p16 and HPV-DNA were positive in all cases, whereas mRNA detection was positive in 9 cases only. The prevalent genotype was HPV16 (9 cases, 75%). Other genotypes were HPVs 58, 33, and 66. Medullary carcinomas of the penis are morphologically distinctive HPV-related high-grade neoplasms affecting older individuals. More studies are necessary to delineate the epidemiological, clinical, and molecular features of this unusual penile neoplasm.

Laser capture microdissection-polymerase chain reaction (LCM-PCR) supported by p16 was used for the first time to demonstrate human papillomavirus (HPV) DNA in histologically specific penile lesions, which were as follows: squamous hyperplasia (12 lesions, 10 patients), flat lesions (12 lesions, 5 patients), condylomas (26 lesions, 7 patients), penile intraepithelial neoplasia (PeIN) (115 lesions, 43 patients), and invasive squamous cell carcinomas (26 lesions, 26 patients). HPV was detected by whole-tissue section and LCM-PCR. LCM proved to be more precise than whole-tissue section in assigning individual genotypes to specific lesions. HPV was negative or very infrequent in squamous hyperplasia, differentiated PeIN, and low-grade keratinizing variants of carcinomas. HPV was strongly associated with condylomas, warty/basaloid PeIN, adjacent flat lesions, and warty/basaloid carcinomas. A single HPV genotype was found in each lesion. Some condylomas and flat lesions, especially those with atypia, were preferentially associated with high-risk HPV. Unlike invasive carcinoma, in which few genotypes of HPV were involved, there were 18 HPV genotypes in PeIN, usually HPV 16 in basaloid PeIN but marked HPV heterogeneity in warty PeIN (11 different genotypes). Variable and multiple HPV genotypes were found in multicentric PeIN, whereas unicentric PeIN was usually related to a single genotype. There was a correspondence among HPV genotypes in invasive and associated PeIN. p16 was positive in the majority of HPV-positive lesions except condylomas containing LR-HPV. p16 was usually negative in squamous hyperplasia, differentiated PeIN, and low-grade keratinizing variants of squamous cell carcinomas. In summary, we demonstrated that LCM-PCR was a superior research technique for investigating HPV genotypes in intraepithelial lesions. A significant finding was the heterogeneity of HPV genotypes in PeIN and the differential association of HPV genotypes with subtypes of PeIN. The presence of atypia and high-risk HPV in condylomas and adjacent flat lesions suggests a precursor role, and the correspondence of HPV genotypes in invasive carcinomas and associated PeIN indicates a causal relation. Data presented support the bimodal hypothesis of penile cancer carcinogenesis in HPV-driven and non-HPV-driven carcinomas and justify the current WHO pathologic classification of PeIN in special subtypes.