Figure 27.1 Steps in Spermatogenesis. (From Trainer TD. Testis and excretory duct system. In: Sternberg SS, ed. Histology for Pathologists. 2nd ed. New York: Lippincott-Raven; 1997:1022.)

Figure 27.2 Testis biopsy showing Sertoli cell only syndrome

Figure 27.3 Testis biopsy showing maturation arrest at the spermatocyte phase

 Figure 27.4 Gross Appearance of Granulomatous Orchitis. The testis has firmer consistency, and is enlarged and vaguely nodular

Figure 27.5 Microscopic appearance of granulomatous orchitis associated with tuberculosis

 Figure 27.6 Pagetoid Extension of Seminoma Into Rete Testis. This should not be misinterpreted as a nonseminomatous component

 Figure 27.7 A, Microscopic appearance of germ cell neoplasia in situ (GCNIS) in routinely stained section. A row of atypical germ cells with clear cytoplasm is seen against a thickened basement membrane. No spermatogenesis is occurring in these tubules. B, Nuclear OCT3/4 expression in GCNIS

 Figure 27.8 Intratubular Embryonal Carcinoma

 Figure 27.9 Classic Seminoma of Testis. Compact nests of large tumor cells are separated by fibrous septa heavily infiltrated by lymphocytes

Figure 27.10 Typical tan, bulging homogeneous appearance of seminoma

Figure 27.11 Seminoma, characterized by uniform cells with clear cytoplasm, sharp cell membranes, and centrally located nuclei, some with flattened edges

Figure 27.12 Seminoma With Cord-Like (Single File) Growth Pattern

Figure 27.13 Seminoma With Microcystic Growth Pattern. A, Hematoxylin and eosin; B, OCT3/4 immunostain

Figure 27.14 Seminoma Associated With Marked Granulomatous Reaction

 Figure 27.15 Seminoma With Trophoblastic Giant Cells. A, Hematoxylin and eosin; B, hCG immunostain

 Figure 27.16 Embryonal carcinoma showing solid nodular cut surface with numerous areas of necrosis and hemorrhage

 Figure 27.17 Embryonal Carcinoma With Papillary Growth Pattern

 Figure 27.18 Embryonal Carcinoma With Overlapping Nuclei and Marked Pleomorphism. Mitotic activity and apoptotic cells are often abundant. Degenerative cells with eosinophilic cytoplasm create an "appliqué" pattern

 Figure 27.19 Post-Pubertal Teratoma. A, Gross appearance. B, Microscopic appearance. Hypercellular stroma is seen growing in a concentric fashion around glandular formations

Figure 27.20 Post-Pubertal Teratoma With Glandular Epithelium and Cartilage

 Figure 27.21 Yolk Sac Tumor With Reticular Pattern

Figure 27.22 Yolk Sac Tumor With Myxoid Spindle Cell and Focal Glandular Patterns

Figure 27.23 Solid yolk sac tumor may mimic seminoma, but cells are more variable in appearance

 Figure 27.24 Microscopic Appearance of Testicular Choriocarcinoma. There is close intermingling of cytotrophoblast and syncytiotrophoblast, which recapitulates that seen in normal chorionic villi

Figure 27.25 Clusters of atypical syncytiotrophoblasts with hemorrhage are NOT diagnostic of choriocarcinoma. The dimorphic relationship to cytotrophoblasts is needed. The background in this case is yolk sac tumor

 Figure 27.26 Cystic Trophoblastic Tumor

Figure 27.27 Somatic Type Malignancy in Teratoma. A low-power field is composed of primitive neuroectodermal tumor (resembling its central nervous system counterpart)

 Figure 27.28 Sarcomatoid yolk sac tumor (expressed SALL4 and glypican-3) behaves similarly to somatic type sarcoma

 Figure 27.29 Embryoid body pattern of mixed yolk sac tumor and embryonal carcinoma

Figure 27.30 Diffuse embryoma pattern of mixed yolk sac tumor and embryonal carcinoma

 Figure 27.31 Seminoma infiltrating into the renal hilar tissue, indicating PT2 disease

 Figure 27.32 Gross Appearance of Spermatocytic Tumor. A large tumor of myxoid appearance bulges on the cut surface

Figure 27.33 Spermatocytic tumor showing admixture of medium-sized cells (predominating), giant cells, and small lymphocyte-like cells

 Figure 27.34 Typical chromatin pattern of spermatocytic tumor

Figure 27.35 Extensive intratubular growth of spermatocytic tumor

 Figure 27.36 Sarcomatous focus in spermatocytic tumor of testis, exhibiting rhabdomyoblastic differentiation. This section is from a lung metastasis

 Figure 27.37 Epidermoid Cyst of Testis. A, The lesion is sharply outlined and contains laminated layers of keratin. B, Microscopic appearance of epidermoid cyst of testis. Keratin squames are laid down by well-differentiated squamous epithelium. There are no skin adnexal structures

 Figure 27.38 Intratesticular well-differentiated neuroendocrine tumor ("carcinoid tumor") showing the classic insular pattern

 Figure 27.39 Gross Appearance of Pure Yolk Sac Tumor in an Infant

 Figure 27.40 Gross Appearance of Leydig Cell Tumor. A, The tumor, which has replaced most of the testis, has a granular yellow appearance. B, This tumor, occurring in a child, is solid, well circumscribed, and dark brown

 Figure 27.41 Leydig Cell Tumor of Testis. The neoplasm is characterized by solid growth of polygonal cells with abundant granular acidophilic cytoplasm

Figure 27.42 Leydig cell tumor with microcystic pattern, which may closely mimic yolk sac tumor

 Figure 27.43 "Testicular Tumor" of the Adrenogenital Syndrome. Multiple nodules are present, divided by fibrous septa

 Figure 27.44 Microscopic appearance of Sertoli cell tumor, not otherwise specified

 Figure 27.45 Sertoli cell tumor, NOS with solid growth, which may mimic seminoma

Figure 27.46 Sclerosing Sertoli Cell Tumor

 Figure 27.47 Gross Appearance of Large Cell Calcifying Sertoli Cell Tumor of Testis. The tumor is distinctly multinodular. The dark nodules had a prominent component of Leydig cells

Figure 27.48 Large Cell Calcifying Sertoli Cell Tumor

 Figure 27.49 Intratubular hyalinizing Sertoli cell neoplasia may be seen in Peutz-Jeghers syndrome

Figure 27.50 Adult form of granulosa cell tumor involving testis. Note the occasional longitudinal grooves, the oval to spindle shape of the tumor cells, and the high mitotic activity

 Figure 27.51 Rare mixed germ cell-sex cord-stromal tumor with Sertoli-like and spermatocytic tumorlike components. (Case courtesy of Dr. Michal Michal, Czech Republic.)

Figure 27.52 Gross appearance of malignant lymphoma of large cell type, which completely replaces the testis

 Figure 27.53 Malignant Lymphoma of Testis. There is diffuse infiltration of the interstitium by neoplastic lymphocytes, which surround and separate atrophic tubules

Figure 27.54 Cases of large B-cell lymphoma with pleomorphic features such as that depicted in this photograph can be misdiagnosed as seminoma, spermatocytic tumor, or embryonal carcinoma

 Figure 27.55 Kaposi sarcoma of the testis in an HIV-infected individual

Figure 27.56 Malignant Melanoma Metastatic to Testis. The black color of the tumor is due to massive melanin deposition

Figure 27.57 Prostatic Adenocarcinoma Metastatic to Testis. This not too rare occurrence is sometimes misdiagnosed as sex cord-stromal tumor

Figure 27.58 Acute and Chronic Epididymitis. The inflammation has not spread to the testicle

Figure 27.59 Granulomatous Epididymitis With Focal Extension Into the Testis. Some of the granulomas have a necrotic center. No micro- organisms were identified on special stains

Figure 27.60 Reactive mesothelial cells in the fibrous wall of a hydrocele, mimicking a neoplasm

 Figure 27.61 Spermatoceles or hydroceles rarely contain aggregates of small blue cells, likely of rete testis origin. They are of no clinical importance

Figure 27.62 Typical gross appearance of adenomatoid tumor of epididymis

Figure 27.63 Adenomatoid tumor, showing typical conglomerate of cystically dilated spaces lined by cuboidal cells, whereas others are lined by flattened cells with the appearance of endothelial cells

Figure 27.64 Adenomatoid Tumor With Epithelioid Features

 Figure 27.65 Adenomatoid Tumor With Typical Keratin Reactivity

Figure 27.66 Mesothelioma infiltrating the testis with a tubular architecture

Figure 27.67 Well-differentiated papillary mesothelioma with a single, cytologically bland lining of cuboidal mesothelial cells

Figure 27.68 Bilateral Clear Cell Papillary Cystadenoma

Figure 27.69 Clear cell papillary cystadenoma has a mixed papillary and tubular architecture with a lining of bland clear cells

Figure 27.70 A rare adenocarcinoma of the epididymis

Figure 27.71 Müllerian type borderline tumor of the paratestis

Figure 27.72 Leiomyosarcoma of the paratestis

Figure 27.73 Meconium periorchitis in a child with cystic fibrosis

Figure 27.74 Vasitis nodosa with benign proliferating ductules deep in the wall of the vas deferens

 Figure 27.75 Smooth muscle hyperplasia of the testicular adnexa with dense sheets of benign smooth muscle cells encasing normal structures

 Figure 27.76 Cellular angiofibroma of the inguinal canal