WHO 2022 classification of penile and scrotal cancers: updates and evolution.

Squamous cell carcinoma (SCC) is the most common malignant tumour of the penis. The 2022 WHO classification reinforces the 2016 classification and subclassifies precursor lesions and tumours into human papillomavirus (HPV)-associated and HPV-independent types. HPV-associated penile intraepithelial neoplasia (PeIN) is a precursor lesion of invasive HPV- associated SCC, whereas differentiated PeIN is a precursor lesion of HPV-independent SCC. Block-type positivity of p16 immunohistochemistry is the most practical daily utilised method to separate HPVassociated from HPVindependent penile SCC. If this is not feasible, the term SCC, not otherwise specified (NOS) is appropriate. Certain histologies that were previously classified as "subtypes" are now grouped, and coalesced as "patterns", under the rubric of usual type SCC and verrucous carcinoma (e.g. usual-type SCC includes pseudohyperplastic and acantholytic/pseudoglandular carcinoma, and carcinoma cuniculatum is included as a pattern of verrucous carcinoma). If there is an additional component of the usual type of invasive SCC (formerly termed hybrid histology), the tumour would be a mixed carcinoma (e.g. carcinoma cuniculatum or verrucous carcinoma with usual invasive SCC); in such cases, reporting of the relative percentages in mixed tumours may be useful. The consistent use of uniform nomenclature and reporting of percentages will inform the refinement of future reporting classification schemes and guidelines/recommendations. The classification of scrotal tumours is provided for the first time in the fifth edition of the WHO Blue book, and it follows the schema of penile cancer classification for both precursor lesions and the common SCC of the scrotum. Basal cell carcinoma of the scrotum may have a variable clinical course and finds a separate mention.

Dataset for the reporting of urinary tract carcinoma-biopsy and transurethral resection specimen: recommendations from the International Collaboration on Cancer Reporting (ICCR).

The International Collaboration on Cancer Reporting (ICCR) is an alliance of major pathology organisations in Australasia, Canada, Europe, United Kingdom, and United States of America that develops internationally standardised, evidence-based datasets for the pathology reporting of cancer specimens. This dataset was developed by a multidisciplinary panel of international experts based on previously published ICCR guidelines for the production of cancer datasets. It is composed of Required (core) and Recommended (noncore) elements identified on the basis of literature review and expert consensus. The document also includes an explanatory commentary explaining the rationale behind the categorization of individual data items and provides guidance on how these should be collected and reported. The dataset includes nine required and six recommended elements for the reporting of cancers of the urinary tract in biopsy and transurethral resection (TUR) specimens. The required elements include specimen site, operative procedure, histological tumor type, subtype/variant of urothelial carcinoma, tumor grade, extent of invasion, status of muscularis propria, noninvasive carcinoma, and lymphovascular invasion (LVI). The recommended elements include clinical information, block identification key, extent of T1 disease, associated epithelial lesions, coexistent pathology, and ancillary studies. The dataset provides a structured template for globally harmonized collection of pathology data required for management of patients diagnosed with cancer of the urinary tract in biopsy and TUR specimens. It is expected that this will facilitate international collaboration, reduce duplication of effort in updating current national/institutional datasets, and be particularly useful for countries that have not developed their own datasets.

[The 2014 consensus conference of the ISUP on Gleason grading of prostatic carcinoma]. / Konsenskonferenz 2014 der ISUP zur Gleason-Graduierung des Prostatakarzinoms.

In 2005 the International Society of Urological Pathology (ISUP) held a concensus conference on Gleason grading in order to bring this grading system up to the current state of contemporary practice; however, it became clear that further modifications on the grading of prostatic carcinoma were necessary. The International Society of Urological Pathology therefore held a further consensus conference in 2014 to clarify these points. This article presents the essential results of the Chicago grading meeting.

[Vancouver classification of renal tumors: Recommendations of the 2012 consensus conference of the International Society of Urological Pathology (ISUP)]. / Vancouver-Klassifikation von Nierentumoren : Empfehlungen der Konsenskonferenz der Internationalen Gesellschaft für Uropathologie (ISUP) 2012.

The 2012 consensus conference of the International Society of Urological Pathology (ISUP) has formulated recommendations on classification, prognostic factors and staging as well as immunohistochemistry and molecular pathology of renal tumors. Agreement was reached on the recognition of five new tumor entities: tubulocystic renal cell carcinoma (RCC), acquired cystic kidney disease-associated RCC, clear cell (tubulo) papillary RCC, microphthalmia transcription factor family RCC, in particular t(6;11) RCC and hereditary leiomyomatosis-associated RCC. In addition three rare forms of carcinoma were considered as emerging or provisional entities: thyroid-like follicular RCC, succinate dehydrogenase B deficiency-associated RCC and anaplastic lymphoma kinase (ALK) translocation RCC. In the new ISUP Vancouver classification, modifications to the existing 2004 World Health Organization (WHO) specifications are also suggested. Tumor morphology, a differentiation between sarcomatoid and rhabdoid and tumor necrosis were emphasized as being significant prognostic parameters for RCC. The consensus ISUP grading system assigns clear cell and papillary RCCs to grades 1-3 due to nucleolar prominence and grade 4 is reserved for cases with extreme nuclear pleomorphism, sarcomatoid and/or rhabdoid differentiation. Furthermore, consensus guidelines were established for the preparation of samples. For example, agreement was also reached that renal sinus invasion is diagnosed when the tumor is in direct contact with the fatty tissue or loose connective tissue of the sinus (intrarenal peripelvic fat) or when endothelialized cavities within the renal sinus are invaded by the tumor, independent of the size. The importance of biomarkers for the diagnostics or prognosis of renal tumors was also emphasized and marker profiles were formulated for use in specific differential diagnostics.

[Diagnostics of radical prostatectomy specimens. Results of the 2009 consensus conference of the International Society of Urological Pathology]. / Diagnostik radikaler Prostatektomiepräparate. Ergebnisse der Konsensuskonferenz der Internationalen Gesellschaft für Urologische Pathologie 2009.

The 2009 consensus conference of the International Society of Urological Pathology (ISUP) made recommendations for standardization of handling and staging of radical prostatectomy specimens. The conference topics were preparation of specimens, the T2 subclassification, prostate cancer volume, extraprostatic tumor extent, lymphovascular invasion, seminal vesicle infiltration, lymph node metastases and surgical margins. This review article presents the essential results and recommendations of this conference.

Dataset for the reporting of carcinoma of the bladder-cystectomy, cystoprostatectomy and diverticulectomy specimens: recommendations from the International Collaboration on Cancer Reporting (ICCR).

The International Collaboration on Cancer Reporting (ICCR) is a not for profit organisation whose goal is to produce standardised internationally agreed and evidence-based datasets for pathology reporting. With input from pathologists worldwide, the datasets are intended to be uniform and structured. They include all items necessary for an objective and accurate pathology report which enables clinicians to apply the best treatment for the patient. This dataset has had input from a multidisciplinary ICCR expert panel. The rationale for some items being required and others recommended is explained, based on the latest literature. The dataset incorporates data from the World Health Organization (WHO) 2016, and also from the latest (8th edition) TNM staging system of the American Joint Committee on Cancer (AJCC). Fifteen required elements and eight recommended items are described. This dataset provides all the details for a precise and valuable pathology report required for patient management and prognostication. This dataset is intended for worldwide use, and should facilitate the collection of standardised comparable data on bladder carcinoma at an international level.

Validation of International Society of Urological Pathology (ISUP) grading for prostatic adenocarcinoma in thin core biopsies using TROG 03.04 'RADAR' trial clinical data.

In 2014 a consensus conference convened by the International Society of Urological Pathology (ISUP) adopted amendments to the criteria for Gleason grading and scoring (GS) for prostatic adenocarcinoma. The meeting defined a modified grading system based on 5 grading categories (grade 1, GS 3+3; grade 2, GS 3+4; grade 3, GS 4+3; grade 4, GS 8; grade 5, GS 9-10). In this study we have evaluated the prognostic significance of ISUP grading in 496 patients enrolled in the TROG 03.04 RADAR Trial. There were 19 grade 1, 118 grade 2, 193 grade 3, 88 grade 4 and 79 grade 5 tumours in the series, with follow-up for a minimum of 6.5 years. On follow-up 76 patients experienced distant progression of disease, 171 prostate specific antigen (PSA) progression and 39 prostate cancer deaths. In contrast to the 2005 modified Gleason system (MGS), the hazards of the distant and PSA progression endpoints, relative to grade 2, were significantly greater for grades 3, 4 and 5 of the 2014 ISUP grading scheme. Comparison of predictive ability utilising Harrell's concordance index, showed 2014 ISUP grading to significantly out-perform 2005 MGS grading for each of the three clinical endpoints.

Prostatic tissue in mature cystic teratomas of the ovary.

We report two examples of mature cystic teratomas of the ovary containing prostatic tissue. Both were incidental findings in teratomas that were otherwise typical at clinical and pathologic levels. The prostatic tissue contained ducts and acini in a simple branching pattern similar to that seen in the peripheral zone of the prostate gland. Transitional cell elements were present in both cases and compact acini resembling Cowper's gland were noted in one. No testicular or Wolffian duct tissue was noted. The immunohistochemical staining pattern of the glands was identical to that seen in normal prostate. In a literature review, four additional cases were identified. The presence of prostatic tissue in a 46XX tumor suggests induction by locally produced androgen. Some investigators have identified luteinized stromal cells and indicated these as the source of this androgen. Other possible androgenic origins include ovarian hilar cells, adrenal cortex, and tumor cells.

Dermoid cyst of the testis: a study of five postpubertal cases, including a pilomatrixoma-like variant, with evidence supporting its separate classification from mature testicular teratoma.

It is controversial if the rare dermoid cyst of the testis should be classified as a variant of mature teratoma or separately. The spectrum of findings is also ill defined, as is the relationship of dermoid cyst to intratubular germ cell neoplasia of the unclassified type (IGCNU). This study therefore reports the findings in five testicular dermoid cysts that occurred in five patients, 17-42 years of age, who presented with testicular masses. Four lesions consisted of a keratin-filled cyst with a thickened wall, whereas one had islands of "shadow" squamous epithelial cells with superimposed calcification and ossification (pilomatrixoma-like variant). Hair was identified grossly in two cases. On microscopic examination, four tumors had hair follicles with sebaceous glands showing a typical, cutaneous-type orientation to an epidermal surface, although no hair shafts were present in two. In addition, the fibrous wall contained smooth muscle bundles (all tumors) and eccrine or apocrine sweat glands (4 tumors). In some cases there were also glands lined by ciliated epithelium (4 tumors, including the pilomatrixoma-like variant), intestinal mucosa (1 tumor), and bone (2 tumors). There was no cytologic atypia or apparent mitotic activity, and no case had IGCNU in the seminiferous tubules. All patients were clinical stage I and were treated by orchiectomy without adjuvant therapy. All were well on follow-up from 1.5 to 9.5 years later. This study supports that dermoid cyst may have noncutaneous teratomatous elements and that an important criterion for its diagnosis is the absence of IGCNU. It also supports that it should be categorized separately from mature testicular teratoma because of the malignant nature of the latter in postpubertal patients. These observations suggest that there are at least two pathways for testicular teratomas in postpubertal patients: the more common being through IGCNU by differentiation from an invasive malignant germ cell tumor and the less common one, taken by dermoid cyst, by direct transformation from a nonmalignant germ cell.

Paneth cell-like change and small cell carcinoma of the prostate. Two divergent forms of prostatic neuroendocrine differentiation.

Paneth cell-like change of the prostate refers to collections of prostatic cells with eosinophilic cytoplasmic granules that bear a striking histological resemblance to normal intestinal Paneth cells. Paneth cell-like change in malignant prostatic epithelium usually represent neuroendocrine differentiation, with neuroendocrine granules confirmed by immunohistochemical and ultrastructural studies. We report the histopathological, immunohistochemical, and electron microscopic findings in a mixed adenocarcinoma with Paneth cell-like change and small cell undifferentiated carcinoma. This case illustrates two divergent forms of neuroendocrine differentiation occurring in a single prostatic neoplasm. The spectrum of neuroendocrine differentiation in the prostate should be expanded to include tumors with Paneth cell-like change in addition to carcinoid tumors and small cell undifferentiated carcinoma. These three distinct forms of prostatic neuroendocrine neoplasia appear to correlate with three size ranges of neuroendocrine granules seen by electron microscopy.

Postatrophic hyperplasia of the prostate gland: a detailed analysis of its morphology in needle biopsy specimens.

Postatrophic hyperplasia is a histologic pattern showing atrophic and hyperplastic glands, sometimes with a small acinar configuration. Because distinction from small acinar carcinoma may be challenging, particularly in needle biopsy specimens, we studied 56 needle biopsy specimens containing 68 foci to ascertain the morphologic spectrum of postatrophic hyperplasia. All foci showed a distinct lobular small acinar proliferation with varying proportions of atrophic and hyperplastic glands. Gland size was typically variable, predominantly of small caliber but occasionally of intermediate to larger caliber. Round, oval, elongated, slitlike and stellate glands were seen. The nuclei were generally regular without hyperchromasia, with rare small nucleoli seen in 10 (15%) foci. The cytoplasm was variable, ranging from scant in atrophic glands to moderate or abundant and clear or occasionally eosinophilic in hyperplastic glands. An irregular internal gland contour was noted in glands with features of both atrophy and hyperplasia. Basal cells were apparent by light microscopy in most foci, although their distribution within foci and between foci varied. This finding was confirmed in all 26 cases studied with the high molecular weight cytokeratin immunohistochemical stain (34betaE12). Associated pathology included adenocarcinoma (12%), high-grade prostatic intraepithelial neoplasia (3%), atrophy distinct from foci of postatrophic hyperplasia (55%), and atypical adenomatous hyperplasia (2%). Adjunctive features of cancer were not seen in any of the foci of postatrophic hyperplasia. Familiarity with the histologic features of postatrophic hyperplasia will allow its confident separation from cancer, especially in limited biopsy material.

Clear cell cribriform hyperplasia of prostate. Report of 10 cases.

We report 10 patients with clear cell cribriform hyperplasia of the prostate. Their ages ranged from 62 to 87 years, with a mean of 72 years. The clinical diagnosis in all patients was benign nodular hyperplasia; all the patients are alive and have shown no evidence of recurrent disease. Follow-ups ranged from 1 month to 7 years (median: 12.5 months; mean: 24.6 months). Pathologically, this lesion has a cribriform arrangement of clear cells with a complex papillary growth simulating the cribriform pattern of prostatic carcinoma. In fact, in five of the 10 cases, the referring diagnosis was either carcinoma or possible carcinoma. Cytologically, however, there is no nuclear atypia, mitosis, or prominent nucleoli, and typically there is a double epithelial cell layer at the periphery of the involved acini. In summary, clear cell cribriform hyperplasia is a benign hyperplastic process with a complex papillary-cribriform structure and should not be confused with prostatic carcinoma. The key feature for the diagnosis is the preservation of nodular configuration with a bland cytology and double cell layer lining the involved acini.

Adenomatous hyperplasia of the rete testis. A clinicopathologic study of nine cases.

Adenomatous hyperplasia of the rete testis is an uncommon lesion that has recently been described. Nine cases of adenomatous hyperplasia were identified in two institutions from 1980 to 1989. At diagnosis the nine patients ranged in age from 30 to 74 years (mean, 59 years; median, 66 years). Three patients presented with a grossly identifiable solid or cystic testicular hilar mass. In six cases adenomatous hyperplasia was an incidental microscopic finding--five from orchiectomy specimens and one from an autopsy specimen. Microscopically, the hyperplasia consisted of a tubulopapillary epithelial proliferation of rete testis. The lining cells were cuboidal to low columnar and lacked nuclear pleomorphism or mitotic figures. The involvement of the rete testis was predominantly diffuse. In seven cases the seminiferous tubules showed atrophic changes. Ultrastructural and immunohistochemical (keratin, epithelial-membrane antigen: positive; vimentin, muscle-specific actin, desmin, and S-100: negative) studies done on one case showed similar features to those of nonhyperplastic rete testis epithelium. No patient with adenomatous hyperplasia showed local recurrence or metastasis. Possible pathogeneses include hormonal imbalance or stimulatory influence that remains as yet unidentified.

Effect of combination endocrine therapy (LHRH agonist and flutamide) on normal prostate and prostatic adenocarcinoma. A histopathologic and immunohistochemical study.

The histopathology of 23 radical prostatectomies from patients with prostatic adenocarcinoma pretreated for 3-6 months with combination therapy including a luteinizing hormone-releasing hormone agonist and the antiandrogen drug flutamide was reviewed and compared with the pretreatment biopsies or transurethral resection material. After combination therapy, benign prostatic glands showed marked atrophy with prominent basal-cell layers, basal-cell hyperplasia, and epithelial-cell vacuolization. Immature squamous-cell metaplasia was present in seven cases. Residual carcinoma, on the other hand, was found in 19 of the 23 cases, and in 8 of these, tumor cells were either vacuolated or had scanty cytoplasm. Residual tumor was present as only one focus in 13 cases, and in 3 of these it was composed of single cells with a "hemangiopericytoma-like" pattern. An immunohistochemical study for prostatic acid phosphatase and prostatic-specific antigen could be carried out on paraffin blocks from 19 biopsies and 18 prostatectomies. After combination therapy, a reduction in staining (intensity and number of positive cells) was observed for the two markers in both normal prostate and carcinoma but with more pronounced effects on the latter. The present data show that temporary combination therapy before radical prostatectomy causes marked and very characteristic changes in normal prostatic tissue as well as in the prostatic tumor. These histologic patterns enter the differential diagnosis of a variety of atrophic, metaplastic, and proliferative lesions of the prostate gland. The pathologist must be aware of these histologic changes when looking at biopsy or resection material of treated patients.

Mixed epithelial and stromal tumor of the kidney.

We describe the clinicopathologic features of 12 patients with a distinctive tumor of the kidney characterized by a mixture of epithelial and stromal elements that form solid and cystic growth patterns. Similar tumors were reported previously in the literature under various names, including adult mesoblastic nephroma. All but one of the patients were women. The only man had a long history of treatment with lupron and diethylstilbesterol. Seven of the women had histories of long-term oral estrogen use of whom six had undergone total abdominal hysterectomy and bilateral salpingo-oophorectomy several years prior, and the seventh patient had been using oral contraceptives for many years. Another woman had this operation but did not receive any hormone therapy. Ages ranged from 31 to 71 years (mean, 56 yrs). Six patients presented with symptoms, including pain and infections attributable to mass effect, and in six the tumor was detected incidentally. Grossly, the tumors were well-circumscribed (mean size, 6 cm; range, 3-12 cm) and consisted of solid and cystic components, most often in equal proportions but in variable distribution. Microscopically, the spindle cell component ranged in appearance from scar-like fibrous tissue to leiomyoma-like interlacing fascicles; usually there was a mixture of both. More cellular foci reminiscent of ovarian stroma or solitary fibrous tumor were also present. No blastema was present. Epithelial elements (composed of clusters of tubules with variable lining) were scattered amidst the spindle cells, and focally transformed into large cysts lined by cells with abundant pink cytoplasm and a hobnail appearance. Immature epithelial elements typical of Wilms' tumor were not present. Muscle markers (desmin and smooth muscle actin) were positive diffusely and strongly in the spindle cells of all tumors, whereas HMB-45 and CD34 were absent. Estrogen receptors were detected in the nuclei of spindle cells in seven tumors and progesterone receptors in three. The distinctive clinicopathologic characteristics of these lesions warrant their classification as a separate category of kidney tumor. We suggest the descriptive term "mixed epithelial and stromal tumor" for this group until its nature and relationship to other kidney lesions are further clarified. Its preponderance in females with a history of long-term estrogen replacement and the history of long-term sex-steroid use in the only male patient, combined with the frequent content of estrogen and progesterone receptors in the spindle cells, suggest that the hormonal milieu plays a role in the evolution of these tumors. The clinical and pathologic parallels with mucinous cystic tumors of pancreas and liver raise the possibility of a common pathogenetic mechanism that may be linked to the periductal fetal mesenchyme. We think this entity is a benign composite neoplasm in which stroma and epithelium are both integral neoplastic components.

Granulocytic sarcoma of the female genital tract: a clinicopathologic study of 11 cases.

Eleven patients, 13 to 76 (mean, 40) years of age, had granulocytic sarcoma of the female genital tract (FGT) (ovary, seven cases; vagina, three cases; cervix, one case). In nine cases, the FGT involvement was the initial clinical presentation of the disease, and in the other two cases, the FGT involvement was discovered during a relapse of acute myeloid leukemia. The tumors ranged from 0.5 to 14 (mean, 7.5) cm in greatest dimension. Two ovarian tumors were bilateral, and three were green. Microscopic examination revealed a predominantly diffuse pattern of growth, but cords and pseudoacinar spaces were also present focally in several cases. Sclerosis was seen in five tumors and was prominent in one. Prominent myeloid differentiation was readily recognizable on routinely stained sections in three cases, whereas the neoplastic cells in the other cases were primitive with only rare eosinophilic myelocytes. All 11 tumors were positive for chloroacetate esterase, nine of nine were strongly and diffusely positive for lysozyme, eight of eight for myeloperoxidase, seven of seven for CD68, and six of six for CD43. Examination of bone marrow or peripheral blood performed after the diagnosis of FGT involvement revealed acute myeloid leukemia in three of five cases. Two of these patients died of disease, 1 and 16 months after the initial diagnosis, and the third, who received chemotherapy, is alive and free of disease 8 months after the initial diagnosis. One of the two patients with negative bone marrow had recurrent granulocytic sarcoma 30 months after diagnosis and died of sepsis 1 month later; no residual disease was noted at autopsy. The other patient is alive and free of disease 18 months after the diagnosis. One of the four remaining patients with primary FGT involvement who did not have a bone marrow biopsy died of leukemia 24 months later; no follow-up information is available for the other three patients. One of the two patients with a prior diagnosis of acute myeloid leukemia was alive with disease 26 months later; follow-up is not available for the second patient. The diagnosis was often difficult in these cases, the most common problem being distinction from malignant lymphoma, but carcinoma, granulosa cell tumor, and, rarely, other tumors were considered. Immunohistochemical and enzyme histochemical staining were useful in establishing the diagnosis, although suspicion of the diagnosis on examination of routinely stained sections was of paramount importance.

Paratesticular serous papillary carcinoma. A report of six cases.

Six intrascrotal, invasive epithelial neoplasms of serous papillary type arose in the paratesticular region of patients 16 to 42 (mean, 30.8) years of age. Five patients, one with an associated hydrocele, presented with a testicular mass and one with a hydrocele only. The serum CA-125 level was elevated in one of the two patients in whom it was measured. Grossly, the tumors were solid, white, or tan, poorly circumscribed, often gritty masses. Four tumors involved primarily the soft tissue between the testis and epididymis (testiculoepididymal groove) and one, the paratesticular soft tissue. The sixth tumor was confined to the visceral tunica vaginalis at the inferior pole of the testis. The most common microscopic pattern was characterized by invasive, well-formed papillae lined by serous cuboidal or columnar cells with eosinophilic cytoplasm and malignant nuclear features. Psammoma bodies were abundant in all the cases. Areas of borderline serous tumor were present in two tumors and predominated in one. Five of five tumors were positive for keratin (AE1/3), S-100, epithelial membrane antigen, and Ber-EP4; three of five for Leu M1 and B72.3; two of five for carcinoembryonic antigen and placental alkaline phosphatase; and one in five for vimentin. Ultrastructural examination in one case demonstrated gland formation with delicate luminal microvilli and cilia. Follow-up information was available in five cases: Three patients are without evidence of disease after relatively short postoperative intervals of 1, 1, and 3 years, although one of these patients has had a persistently elevated CA-125 level. Two patients had recurrence of their tumors 4 and 7 years after diagnosis, one with diffuse abdominal spread, the other in a cervical lymph node. The latter patient died of his disease 5 years after diagnosis.

Q-fever. The liver and bone marrow pathology.

Eighteen liver and seven bone marrow biopsies from 44 patients with clinically and serologically proven Q-fever seen during a recent outbreak were studied. Highly distinctive fibrin-ring granulomas were found in seven liver and four bone marrow specimens. Lipid or nonspecific granulomas often containing neutrophils and variable numbers of giant cells were noted in 13 livers and seven bone marrows. A wide variety of nongranulomatous histological changes, frequently including steatosis and nonspecific "reactive" hepatitis, were seen in the liver biopsies. Identifiable rickettsiae were not present in tissue sections studied by microbiologic stains or electron microscopy. The histological response pattern to Coxiella infection is varied, and Q-fever should always enter the differential diagnosis of a granulomatous disease encountered in liver and bone marrow specimens.

Sclerosing adenosis of the prostate gland. A lesion showing myoepithelial differentiation.

Sclerosing adenosis of the prostate is a rare lesion characterized by the proliferation of variably sized glands in a cellular stroma. We report light microscopic, immunohistochemical, and ultrastructural studies in 22 examples from 15 patients. Two cases were identified in 100 consecutive prostates embedded by a whole organ method, giving a prevalence of 2%. Antibodies directed against the following antigens were used: high-molecular-weight cytokeratin (CKH; 34 beta E12); cytokeratin (CK; AE1/AE3), prostatic acid phosphatase (PAP), prostate-specific antigen (PSA), S-100 protein, muscle-specific actin (HHF35), and vimentin (Vim). Cells within the glandular component demonstrated positive reactivity for CK, CHH, PSA, and PAP, indicating a prostatic epithelial origin. In addition, a distinct population of cells reacting for muscle-specific actin and S-100 protein was identified within this glandular element. Adequate material for ultrastructural study was available in five cases; all showed the presence of flattened cells located between the basement membrane and secretory epithelial cells, which had features typical for myoepithelial differentiation. Although the prostate gland does not normally contain myoepithelial cells, we have documented their consistent presence in this unusual lesion; we believe these cells arise by a metaplastic process from the prostatic basal cells.

Sex cord-stromal tumors of the testis with entrapped germ cells: a lesion mimicking unclassified mixed germ cell sex cord-stromal tumors.

The authors describe 10 sex cord-stromal tumors of the testis that incorporated germ cells, thereby mimicking the unclassified type of mixed germ cell sex cord-stromal tumor (MGCSCST). These neoplasms occurred in patients from 3 to 48 years old (mean age, 26 years) who presented with testicular masses. On microscopic examination, nine tumors had a combination of tubular and cord-like arrangements of sex cord cells with transition to spindle-shaped tumor cells. They were diagnosed as either unclassified sex cord-stromal tumors (n = 5) or Sertoli-stromal cell tumors (n = 4). One tumor was a pure Sertoli cell tumor. The admixed germ cells were usually at the periphery and in clusters, but occasionally were in the center or more diffuse. In nine patients the germ cells resembled spermatogonia, having round nuclei with uniform, dusty chromatin and inconspicuous or small nucleoli. None of these cells stained with a variety of markers used for neoplastic germ cells, and in one case in which the non-neoplastic Sertoli cells were strongly reactive for inhibin but the neoplastic Sertoli cells were not, all the germ cells within the tumor occurred adjacent to inhibin-positive Sertoli cells. With static cytophotometry, a diploid deoxyribonucleic acid content was found in these germ cells in the two investigated cases. In one case the germ cells had the morphologic appearance of seminoma cells and they stained positively for the markers of neoplastic germ cells. This case was interpreted as a "collision" tumor between a Sertoli cell tumor and a seminoma. The authors conclude that sex cord-stromal tumors with entrapped germ cells of the testis are more common than unclassified MGCSCSTs--a bona fide testicular example of which has not been seen by any of the authors.