
Last revised 10 August 2008
Copyright © 2002-2008, PathologyOutlines.com, Inc.
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Testis: primary references
Testis: embryology, anatomy, cryptorchidism, atrophy, gonadotropin deficiency, testotoxicosis, biopsy
Infertility: general, normal spermatogenesis, hypospermatogenesis, maturation arrest, germ cell aplasia, Klinefelter’s, de la Chapelle’s, tubular sclerosis, excurrent duct obstruction
Intersex syndromes: general, androgen insensitivity, congenital adrenal hyperplasia, dysgenetic male pseudohermaphroditism, gonadal dysgenesis-general, mixed, pure; male pseudohermaphroditism, persistent mullerian duct, testicular regression, true hermaphroditism
Infectious lesions: AIDS, brucellosis, gonorrhea, Histoplasma, leprosy, mumps, pyogenic epididymo-orchitis, syphilis, TB
Non-neoplastic lesions: adrenal cortical rests, anorchia, chemotherapy, chylocele, cystic dysplasia, cysts, epidermoid cyst, granulomatous orchitis, hematocele, hydrocele, juvenile xanthogranuloma, macroorchidism, malakoplakia, meconium periorchitis, necrotizing vasculitis, nodular and diffuse fibrous proliferation, polyorchism, radiation effects, silicon implants, sinus histiocytosis with massive lymphadenopathy, spermatocele, splenogonadal fusion syndrome, varicocele, vasculitis
Neoplasms: general, classification
Germ cell tumors: general, isochromosome 12p, intratubular germ cell neoplasia, post-chemotherapy, seminoma, spermatocytic seminoma, NSGCT-general, carcinoid, choriocarcinoma, diffuse embryoma, embryonal carcinoma, mixed, placental site trophoblastic tumor, PNET, polyembryoma, teratocarcinoma, teratoma, yolk sac tumor
Sex cord-stromal tumors: general, fibromas, granulosa cell (adult, juvenile), Leydig cell, mixed germ cell-sex cord, mixed/unclassified sex cord, Sertoli cell-general, Sertoli hyperplasia, Sertoli-infantile testis, Sertoli adenoma, Sertoli tumor NOS, Sertoli-sclerosing, Sertoli-large cell calcifying, Sertoli-Leydig, adrenogenital syndrome
Other tumors: adenoid cystic carcinoma, anaplastic lymphoma, angiosarcoma, Brenner tumor, chondrosarcoma, granulocytic sarcoma, hemangioma, interdigitating dendritic cell tumor, leukemia, lymphoma, mesothelioma, metastases, mucinous cystadenocarcinoma, myeloid tumor, ossified intratesticular mucinous, osteosarcoma, pilomatricoma, plasmacytoma
Miscellaneous: staging, features to report, grossing
Paratesticular tumors: desmoplastic small round cell, leiomyosarcoma, liposarcoma, lymphoma, ovarian surface epithelial, paratesticular multicystic mass of Wolffian origin, rhabdomyoma, rhabdomyosarcoma, serous borderline tumor, serous papillary carcinoma, smooth muscle hyperplasia
Epididymis: normal, epididymitis
Non-neoplastic lesions: cribriform hyperplasia, epidermoid cyst, granulomatous ischemic lesion, hernia sac, hyaline globules, necrotizing vasculitis, spermatic granuloma, spermatocele
Epididymal tumors: adenocarcinoma, adenomatoid, melanotic neuroectodermal, mesothelioma, miscellaneous, papillary cystadenoma, rhabdomyoma
Spermatic cord: normal, hernia sac, torsion, vasitis nodosa, proliferative funiculitis
Tumors: general, aggressive angiomyxoma, angiomyofibroblastoma, embryonal rhabdomyosarcoma, hemangioma, lipoma, liposarcoma, MFH, paraganglioma, vascular myxolipoma
AJCC Cancer Staging Manual (6th Ed)
Am Journal of Clinical Pathology (AJCP), June 1982 to Aug 2003 - no images
Am Journal of Surgical Pathology (AJSP), Mar 1977 to Aug 2003
Archives of Pathology and Lab Medicine (Archives), Jan 1976 to Aug 2003
Human Pathology (Hum Path), Mar 1970 to July 2003
Modern Pathology (Mod Path), Jan 1988 to Aug 2003
Robbins Pathologic Basis of Disease (6th Ed)
Rosai, J: Ackerman’s Surgical Pathology (8th Ed); Mosby-Year Book, Inc., 1996
Sternberg, S: Diagnostic Surgical Pathology (3rd Ed); Lippincott Williams & Wilkins, 1999
www.WebPathology.com (free GU website with beautiful pictures)
Please refer to these primary references for more detailed discussions and photographs
Histology of testis through development
Birth to age 4 (static phase): Seminiferous tubules filled with small cuboidal cells with no definite lumen present, Leydig cells usually not visible
Age 4-10 (growth phase): tubules, tubular lumina and cells enlarge; tubules become tortuous
Age 10 to puberty (maturation phase): tubular cells have mitoses; Leydig cells prominent; spermatocyte differentiation visible
Adult (post-puberty): each testis weights 15-19g, measures 5 x 3 cm; takes 70 days for cells to mature from spermatogonium to primary spermatocyte to secondary spermatocyte to spermatid to spermatozoa; maturation is orderly along length of tubule, but often not present in biopsy cross section
Reference: AJSP 2003;27:469
Embryology of testis
Presence of Y chromosome (possibly sex determining region Y) determines formation of testis
Germ cells migrate to genital ridge, tubules formed by day 45; wolffian ducts (form epididymis, vas deferens, seminal vesicles) develop by day 25, mullerian ducts (form uterus and upper vagina) by day 43
If no Y, gonad becomes an ovary; if Y present becomes a testis
If Y present, Sertoli cells develop from genital ridge and secrete anti-mullerian hormone / Mullerian inhibiting factor (AMH) by day 62, causing ipsilateral regression of mullerian duct by day 75-80; lack of Sertoli cells means no AMH, no regression and presence of uterus and upper vagina
If Y present, Leydig cells arise by day 64 and produce testosterone, which causes development of Wolffian duct structures (epididymis, vas deferens, seminal vesicles) if functional androgen receptors are also present
If no testosterone is produced, Wolffian duct structures degenerate
Exogenous androgens or their production by maternal tumor or congenital adrenal hyperplasia cause development of Wolffian duct system regardless of presence of Y chromosome
Development of external genitalia requires testosterone plus androgen receptors plus 5 alpha reductase, which converts testosterone to dihydrotestosterone (DHT), which causes development of external genitalia between days 120-140, including elongation of phallus
If ovaries or no gonads present, internal ducts are female
If DHT not present, external genitalia is female
Paired organ suspended in scrotum by spermatic cord
Each testis is attached to an epididymis, which connects rete testis to vas deferens
Testis is composed of convoluted seminiferous tubules in a stroma with Leydig cells
Three layers: outer serosa (tunica vaginalis, extension of peritoneal cavity) with mesothelial cells; tunica albuginea (tough fibrous septa that extends into testis and separates it into 250 lobules of 1-4 seminiferous tubules), inner tunica vasculosa
Seminiferous tubules converge into rete testis at hilum, anastomose into efferent tubules that penetrate tunica albuginea to form head of epididymis
Drawings: image1, image2, image3, image4, image5, image6 image7, image8, image9, image10
Gross images: image1
Efferent ducts: image1, image2
Epididymis (see below):
Interstitium: contains Leydig cells and stromal elements (collagen and myoid cells that surround seminiferous tubules)
Leydig cells: single (20 microns) or in clusters between seminiferous tubules, produce testosterone in response to luteinizing hormone (LH); often associated with nerve fibers and blood vessels; have abundant pink cytoplasm with lipid, lipochrome pigment, Reinke crystalloids (hexagonal prisms by EM), round nuclei with distinct nucleoli; fewer Leydig cells in elderly
Micro image: image1
Mediastinum: posterior testicular capsule with vasculature, nerves, mediastinum of rete testis (where tubules converge)
Rete testis: at testicular hilum; complex tubular architecture may resemble teratoma; connects testicular tubules to 12-15 ciliated efferent ducts, which merge into a single duct, the epididymis at its head; rete lined by flattened to columnar epithelium with numerous microvilli; efferent duct lumina are narrower than epididymis, lined by ciliated columnar cells with microvilli
Micro images: image1, image2, image3, image4
Seminiferous tubules: 150-250 microns in diameter; lined by multilayered epithelium with most mature cells towards lumina; have basal lamina, outer myoid cells (positive for desmin, muscle specific actin, vimentin) and collagen; contain Sertoli cells, spermatogonia (types A and B), primary spermatocytes, secondary spermatocytes, spermatids and spermatozoa; all except spermatozoa are held together by a narrow cytoplasmic bridge
Immature tubules are positive for alpha inhibin
Micro images: image1, image2, image3, image4, image5, image6
Sertoli cells: columnar, on basement membrane, surround germ cell elements with cytoplasmic extensions, form blood-testis barrier; 7% of tubular cells; may contain Charcot-Bottcher crystalloids (bundles of microfilaments); have irregular, highly folded nuclei with prominent nucleoli; produce anti-mullerian hormone, which causes regression of mullerian duct structures in utero; after birth, secrete androgen-binding protein and are responsive to FSH; also produce inhibin
Vas deferens: see below
Vestigial remnants:
Appendix epididymis: remnant of mesonephric duct
Appendix testis (hydatid of Morgani)
Remnant of mullerian duct; attached to tunica albuginea at upper testicular pole; present in 90% of males
May undergo hemorrhagic infarction from twisting on its pedicle
Gross: round/oval, 1-10 mm, pedunculated
Micro: columnar epithelium with vascular fibrous core with smooth muscle cells; may have glandular-like structures due to surface invaginations
Paradidymis (organ of Giraldes): remnant of mesonephric tubules
Vas aberrans (organ of Haller): remnant of mesonephric tubules
Permanent retention of testis outside scrotum
Due to complete or incomplete failure of intra-abdominal testes to descend into scrotal sac, occasionally associated with other GU malformations such as hypospadias
Occurs in 10% of newborn boys, 1% of 1 year old boys; associated with trisomy 13
Testicular descent occurs in 2 phases: (1) abdomen to pelvic brim, controlled by anti-mullerian hormone; (2) pelvic rim to scrotum, androgen dependent, may be mediated by androgen induced release of calcitonin gene-related peptide from genitofemoral nerve
Cryptorchid testis usually (80%) found in inguinal canal; usually is no apparent hormonal disorder
Bilateral in 25% of cases
Cryptorchid testis are prone to trauma, torsion, inguinal hernia (10-20% of cases), sterility
Associated with 5-50x increased risk of testicular carcinoma, usually seminoma (higher risk if abdominal vs. inguinal location); may have cancer in normal descended testes too; biopsies suggested of both testes to detect intratubular germ cell neoplasia (50% with positive biopsy develop germ cell tumor at 5 years vs. minimal with negative biopsy)
Orchiopexy (placement in scrotal sac) should be done before age 2-3 to reduce risk of malignancy; deficient spermatogenesis persists in 10-60%; better fertility if orchiopexy done at younger age
Gross: small, firm, brown testis
Micro: marked hyalinization and thickening of tubular basement membrane, prominent Leydig cells, often hyperplastic Sertoli cells with atrophy of other cells (arrest in germ cell development); variable intratubular germ cell neoplasia; other testis often has paucity of germ cells; may have nodules of hyperplastic Sertoli cells or clusters of persistent immature tubules (“Pick’s adenomas”)
References: Hum Path 1980;11:666
Causes: atherosclerosis (Archives 1985;109:663), mumps or other inflammatory orchitis (particularly if post-pubertal), cryptorchidism, hypopituitarism, cachexia, semen outflow obstruction, radiation, chemotherapy (cyclophosphamide), female sex hormones, hepatic cirrhosis (causes elevated serum estrogen), exhaustion after persistent FSH stimulation, Klinefelter’s syndrome, the nematocide dibromochloropropane, AIDS (AJCP 1990;93:196), testicular regression syndrome
Testicular regression syndrome: patient has only rudimentary epididymis and spermatic cord with vas deferens; testicular tissue is replaced by fibrovascular nodule (mean 1.1 cm), also calcification, hemosiderin; due to cryptorchidism, possibly testicular infarct, Archives 2000;124:694
Post-vasectomy: thickening of tubular wall, reduced spermatids, reduced Sertoli cells, variable interstitial fibrosis
Gross images: atrophy (comparison to normal testis)
Micro: small tubules, thick basement membranes, few/no germ cells; interstitial fibrosis, often increased Leydig cells
Micro images: image1, image2, image3
For normal function, require intact axis of GnRH to FSH/LH
Prepubertal:
Delayed puberty: failure of adolescent development by age 16
Deficiency if gonadotropins were never secreted normally
Most patients with associated syndromes have major congenital anomalies
Kallmann’s syndrome: young adults/teenagers with prepubertal testes, anosmia/hyposmia (loss/reduction in sense of smell), cleft lip/palate, color blindness, short fourth metacarpals
LH mutation preventing binding to receptor: high LH, normal FSH, low testosterone, no Leydig cells, maturation arrest
Treatment: exogenous FSH and LH produce normal appearing and functioning testes
Micro: resembles prepubertal child; small testes without lumina, prepubertal Sertoli cells, scattered spermatogonia; no recognizable Leydig cells
Postpubertal:
Selective LH deficiency: normal FSH, active spermatogenesis with normal tubules, low LH and testosterone, low semen volume, reduced/absent Leydig cells
Selective FSH deficiency: normal LH, normal testosterone, variable sperm counts, low FSH, infertile with hypospermatogenesis, spermatogenesis with germ cell aplasia and incomplete maturation arrest
Other causes: pituitary or hypothalamic trauma, surgery, tumors, radiation, androgens / estrogens
Histology progresses from incomplete to complete maturation arrest, germ cell hypoplasia, germ cell aplasia, sclerotic tubules; tubules have thick/fibrotic walls, may have loss of Leydig cells
High dose estrogens for sex-change patients cause immature Sertoli cells, germ cell hypoplasia and Leydig cell atrophy
Low dose estrogens for prostate adenocarcinoma cause maturation arrest and partial Leydig cell atrophy
Treatment: FSH and LH produce normal appearing and functioning testes
Form of male sexual precocity with active Leydig cell differentiation and premature onset of spermatogenesis without pituitary gonadotropin stimulation
Due to apparent inherited intratesticular defect
Micro: Leydig cells appear fully differentiated; no Reinke crystals; germ cells at all stages of spermatogenesis present but with disordered maturation; structural abnormalities in spermatids
References: Archives 1985;109:990
Most biopsies have 3-5 lobules plus septa of tunica albuginea
Usually see many spermatozoa, “perfect” tubules mixed with occasional tubules with scattered “disorganized “ spermatogenesis
In young men, ratio of germ cells to Sertoli cells is usually 13:1
Indicated for azoospermia (no sperm present) without endocrine abnormalities, since biopsies may show focal spermatogenesis
Multinucleated giant stromal cells are associated with testicular atrophy due to estrogens
Hyalinized tubules with elastic fibers indicate hyalinization developed post-puberty
Zenker’s and Bouin’s fixative is preferred, as formalin introduces significant artifact
Biopsy results for azoospermia:
Germ cell aplasia/Sertoli cell only syndrome (29%): tubular basement membrane thickening, no germ cells, usually normal number of Leydig cells
Spermatocytic arrest (26%): usually early (no spermatids, no spermatozoa), normal Leydig cells; may be late (no spermatozoa only)
Generalized fibrosis (18%)
Normal (27%): usually associated with bilateral obstruction as seen in Young’s syndrome (also chronic sinopulmonary infections) or testicular blockage (50% of tubules lack lumina; disorderly maturation of germ cells); surgery (epididymovasotomy, vasovasotomy) is often successful
Azoospermia due to known obstruction: usually reduction in spermatids only due to increased hydrostatic pressure (47%), severity related to cause/span of obstruction; also normal testes (28%), reduction of primary spermatocytes and spermatids (9%), reduction in all germ cell types (13%), hyalinization (2%), AJSP 1999;23:1546
Biopsy results for no sperm count due to endocrine abnormalities:
Hypogonadotrophic eunuchoidism (60%): low FSH and LH levels; small infantile tubules with few/no Leydig cells, scattered spermatogonia and Sertoli cells
Klinefelter’s syndrome (30%): XXY karyotype, tubular fibrosis, prominent basement membrane thickening and Leydig cell hyperplasia; associated with increased incidence of breast carcinoma, possibly Leydig cell tumors, mediastinal germ cell tumors
Testicular aplasia: high urinary LH and FSH
Biopsy results for oligospermia:
Incomplete spermatocytic arrest: some tubules normal, some with arrest
Regional or incomplete fibrosis
Spermatogenic hypoplasia: tubules with reduced number of germ cells that are also disordered
Tubular hyalinization: includes Kleinfelter’s syndrome (small diameter tubules with thickened basement membrane and increased Leydig cells)
Normal: associated with duct obstruction
Sloughing and disorganization: lumina contain desquamated immature cells, disorganized spermatogenesis (associated with hypoplasia, duct obstruction and mechanical damage to specimen)
Other causes of oligospermia: varicocele, cystic fibrosis causing obstruction in epididymis and vas deferens
Fine needle aspiration (FNA):
Used to differentiate normal testis, hypospermatogenesis, early and late maturation arrest, Sertoli cell only patterns
Minimally invasive, may replace testis biopsy
2-11 aspiration sites, 10-30 needle excursions/site; adequate if 100 clusters of 20 or more testis cells
May be more representative than biopsy since more sampling
Interpretation should focus on relative abundance of germ cells (primary spermatocytes, spermatids, mature sperm with tail) and Sertoli (support) cells
Frequency of clinical diagnoses: idiopathic non-obstructive (50%), varicocele (18%), genetic (8%), cryptorchidism (8%), cancer (8%), obstruction (7%), Kartageners syndrome (1%)
Hypospermatogenesis: presence but paucity of all germ cell types
Sertoli cell only: no primary spermatocytes, no spermatids, no spermatozoa
Early maturation arrest: primary spermatocytes but no spermatids, no spermatozoa
Late maturation arrest: all cells but spermatozoa
Note: FNA cannot assess basement membrane, which is important for neoplasm and CIS diagnoses
References: AJSP 2001;25:71
Infertility
Causes: pretesticular, testicular, post-testicular
Pretesticular: extragonadal endocrine disorders (hypothalamic, pituitary, adrenal); includes elevated prolactin levels
Testicular: (see below), little treatment currently available
Posttesticular: duct obstruction (congenital, inflammatory, postsurgical); surgical treatment often successful since spermatogenesis is normal
Note: impaired sperm motility due to epididymal or immunologic factors is considered posttesticular
Evaluation: history and physical examination, semen analysis, WBC count in semen, detection of anti-sperm antibodies, sperm function tests (cervical mucus interaction, ova penetration, hemizonal assay)
Testicular biopsy is helpful for azoospermia without endocrine abnormalities
RNA binding motif: nuclear immunostain identifies spermatogenesis in biopsies that appear to be Sertoli cell only, Hum Path 2001;32:36
References: AJSP 2001;25:71, Archives 1995;119:722, Archives 1984;108:35
Not every tubule has complete spermatogenesis
Number of late spermatids correlates best with sperm counts
Some patients have normal sperm counts but low motility or duct obstruction; EM may show round-headed sperm or immotile-cilia syndrome
Reduced spermatogenesis (reduction in number of germ cells, thin epithelial layer) without a focal point of arrest
Mild if changes in occasional tubules; severe if significant reductions in all tubules
Often is thickening of tunica propria, interstitial fibrosis, tubular sclerosis, germ cell disorganization and sloughing into lumina
Not specific as to etiology; differential diagnosis includes toxins, excess heat, varicocele, hypothyroidism
References: Archives 1982;106:231
Complete maturation arrest: germ cell maturity ceases at a specific point; sperm counts usually zero
Incomplete maturation arrest: similar to complete but a few late spermatids are present in a few seminiferous tubules; patients are usually oligospermic
Same etiologies as hypospermatogenesis; also postpubertal gonadotropin deficiency, alkylating agents, radiation therapy
Non-zero sperm counts indicate late spermatids are present somewhere in testis, although perhaps not in area biopsied
Micro: numerous spermatogonia, few spermatocytes, no mature spermatozoa; Sertoli cells prominent since reduced germ cells; tubules often contain degenerated cells with irregular dense nuclei
Micro images: image1
Aka Sertoli cell only syndrome
Charcot-Bottcher crystals sometimes seen as thin eosinophilic lines in various directions
Causes: del Castillo’s syndrome (normal serum testosterone, normal secondary sex characteristics, high normal FSH, soft small testes, azoospermia), gonadotropin deficiency, cryptorchidism, orchitis, prostate cancer hormonal therapy
Micro: tubules are reduced in diameter and lined only by post-pubertal Sertoli cells; Sertoli cells are perpendicular to basement membrane; may resemble palm trees waving in a breeze; cells have nuclear indentations and prominent nucleoli
DD: intratubular germ cell neoplasia, post-chemotherapy (alkylating agents), post-radiation therapy
Germ cell aplasia and focal spermatogenesis
Two populations of tubules; one population with small tubules exhibiting germ cell aplasia, other population has reduced spermatogenesis
Usually very low sperm count
47XXY, reduced body and pubic hair, gynecomastia in 40-80%, high FSH, variable LH
Increased risk of breast cancer
Gross: small, firm testes
Micro: reduced number of intratubular germ cells, some tubules are Sertoli cell only; also tubular sclerosis, Leydig cell nodules (appear hyperplastic due to tubular atrophy), focal spermatogenesis
Micro images: image1, image2, image3
EM: no annulate lamellae in Sertoli cells; microcrystal formation but no Reinke crystal’s in Leydig cells, Archives 1982;106:228
46XX with de la Chapelle’s syndrome
Small stature (smaller than Klinefelter’s), sparse pubic and facial hair, occasional gynecomastia, possibly reduced size of testes, prostate, penis; high FSH and LH, low testosterone; may be due to XXY with loss or translocation of Y during development
Tubular sclerosis / interstitial fibrosis only
Seen in association with hypospermatogenesis, cryptorchidism, karyotypic abnormalities
Rare to have biopsies with only this finding
Due to FSH/LH deficiency, remote chronic orchitis, remote ischemia, idiopathic
Excurrent means distal to rete testis
Congenital or acquired
Occurs in 10% of biopsies for infertility
Associated with azoospermia, normal-sized testes and active (but not necessarily normal) spermatogenesis
Congenital: agenesis or atresia of epididymis or vas deferens, atrophy from secretions in cystic fibrosis
Acquired: infection, sterilization, inadvertent surgical ligation of vas deferens
Partial excurrent duct obstruction is likely if sperm count is appreciably lower than that expected from biopsy
Micro: active spermatogenesis, germ cell disorganization and sloughing; variable interstitial fibrosis and sperm granulomas; no tubular basement membrane thickening
Reference: AJSP 1999;23:1546
Discordance between genetic sex, gonadal sex, genital tract sex or phenotypic sex
Photograph and label specimen and orient with surgeon
6% incidence of intratubular germ cell neoplasia (IGCN) unclassified, AJSP 1993;17:1124
Androgen insensitivity syndrome
Called testicular feminization if complete
Most frequent cause of male pseudohermaphroditism; either XY or XXY
Lack of androgen receptor due to mutations in gene on X chromosome, causes tall phenotypic female with well-formed breasts, absent/scanty pubic and axillary hair, shallow vagina and lack of upper vagina because anti-mullerian hormone (AMH) causes mullerian duct regression
Patients also have bilateral cryptorchidism with intraabdominal, inguinal or labial testes; usually no wolffian or mullerian derivatives
Recommend gonadectomy by puberty since associated with germ cell tumors (30% by age 50)
Case report of associated seminoma, Mod Path 1993;6:89
Gross: tan-brown testes with multiple white nodules of Sertoli cells and wolffian/mullerian duct cysts at lateral pole of testis
Micro: small seminiferous tubules without lumina composed of Sertoli cells only, usually immature, with sparse spermatogonia, marked Leydig cell hyperplasia (often without Reinke’s crystals), ovarian type stroma; nodules are probably hamartomas of Sertoli cells
Congenital adrenal hyperplasia
Due to various enzymatic defects that cause different patterns of synthesis of glucocortical, mineralocorticoid and sex-hormone synthesis
Genetic males have cryptorchidism, viable wolffian duct structures, female or ambiguous genitalia, no mullerian duct structures
Testes resemble cryptorchid testes
May have bilateral Leydig cell hyperplasia with 21-OHase, 11-OHase and 17beta-hydroxysteroid dehydrogenase deficiencies; treat with corticosteroids or surgical excision
Dysgenetic male pseudohermaphroditism
Bilateral dysgenetic testis, mullerian structures, cryptorchidism, inadequate virilization
May be XO/XY mosaics
Infertile, no spermatogenesis