pISSN 1598-298X / eISSN 2384-0749 J Vet Clin 36(1) : 78-81 (2019)
http://dx.doi.org/10.17555/jvc.2019.02.36.1.78
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Clinical, Morphological and Immunohistochemical Characteristics of Canine Lipid-Rich Sertoli Cell Tumor
Chul-Ho Park and Chang-Ho Son1
College of Veterinary Medicine, Chonnam National University, Gwangju 61186 Korea (Received: January 02, 2019 / Accepted: January 24, 2019)
Abstract : Some canine typical Sertoli cell tumors (SCT) induce signs of hyperestrinism. However, whether variant lipid-rich SCTs have signs of hyperestrinism remains largely unknown. In the present study, an 11-year-old male Pekingese dog showed significantly elevated serum estrogen and characteristic signs of hyperestrinism such as gynecomastia and alopecia. Cytological, radiological and ultrasound examinations found testicular mass, prostatitis with squamous metaplasia, and cystitis. Pathologically, the tumor lesions consisted mainly of lipid-rich tumor cells with signet-ring appearance, which were immunohistochemically positive for vimentin and anti-Müllerian hormone. Based on the findings, a diagnosis of lipid-rich Sertoli cell tumor was established. In conclusion, a canine lipid-rich SCT induced signs of hyperestrinism and caused prostatitis via squamous metaplasia due to its excessive secretion of estrogen.
Key words : hyperestrinism, lipid-rich Sertoli cell tumor, canine.
Introduction
Canine testicular tumors are common, and a steady increase in their incidence has been reported (1,8). Testicular tumors originate from germ cells or sex-cord stromal elements of the testis and are categorized into four general groups; germ cell tumors including seminoma, teratoma, embryonal carci- noma, and yolk sac carcinoma from the germinal epithelium of the seminiferous tubules; sex-cord stromal tumors includ- ing Sertoli cell tumor (SCT) and Leydig (interstitial) cell tumor; mixed germ cell sex-cord stromal tumors; and pri- mary tumors not specific to the testis (1). SCTs can be clas- sified into typical and variant lipid-rich forms (3). Typical SCTs are known to cause signs of hyperestrinism in approxi- mately 25% cases, characterized by any combination of feminization, gynecomastia and/or squamous metaplasia of the prostate gland, often accompanied with suppurative pros- tatitis, alopecia, and bone marrow atrophy (1). However, whether lipid-rich SCTs induce signs of hyperestrinism remains unknown. Here, we reported the clinical, morpho- logical, and immunohistochemical characteristics of canine lipid-rich SCT with hyperestrinism.
Case
An 11-year-old Pekingese dog was admitted with a history of hyperestrinism including gynecomastia, pendulous prepu- tial sheath, and bilateral symmetrical alopecia with hyperke- ratinization. Radiologic and ultrasonographic examinations revealed a radiodense nodule in the left testis and hypere-
choic prostatic hyperplasia with central cystic structure con- taining echogenic fluid (Figs 1A-1B), respectively. Fluid content from the prostate cyst and urine sediment obtained from the urinary bladder were obtained by needle biopsy, smeared on cline slides and then stained with Diff-Quick stain. The cytological examinations showed large number of desquamated keratinocytes, neutrophils, and bacteria colo- nies with micrococci and bacilli, indicative of suppurative prostatitis and urinary infection (Figs 1C-1E). Serum estro- gen levels were 117.7 pg/ml, exceeding the normal range of 30.5-66.6 pg/ml.
Gross examination revealed severe atrophy of the right tes- tis (1.2 × 1.0 cm) with normal architecture, whereas the left testis (2.0 × 1.2 cm) showed slight protrusion from the tunica albuginea below head of the epididymis. On the cut surface, 0.9 × 0.9 cm diameter whitish tumor mass was measured (Fig 2A). The tumor was round, well circumscribed, and showed multilobular appearance (Fig 2A). Both testes were fixed in 10% neutral buffered formalin and embedded in paraffin.
Sections (3-5μm) were stained with hematoxylin and eosin.
Upon microscopic examination, the tumor mass was found to be composed of round cells that formed nests separated by fibroconnective tissue capsule (Figs 2B-2C). The tumor cells had large cytoplasmic vacuoles, resulting in the displace- ment of nucleus to the peripheral areas resembling that of a signet ring (Fig 2C). Few elongated spindle-shape tumor cells at the periphery that closely resembled Sertoli cells were intermingled with lipid-rich cells (Fig 2D). Tumor lesions lacked mitotic activity, cytologic atypia, necrosis, and hemorrhage.
To further characterize the contents inside the cytoplasmic vacuoles observed in most tumor cells, periodic acid-Schiff (PAS) reaction was performed using 5μm sections of tumor and canine intestines from archives of paraffin-embedded
1Corresponding author.
E-mail : chson@jnu.ac.kr
Clinical, Morphological and Immunohistochemical Characteristics of Canine Lipid-Rich Sertoli Cell Tumor 79
blocks after the standard procedures. Canine small intestine used as a positive control showed PAS-positive reaction in the cytoplasm of goblet cells, whereas none of the tumor cells in the tumor lesion showed PAS-positive reaction (Fig 3A). To determine the origin of tumor cells, immunohisto- chemistry was performed using the Dako REALTM EnVi- sionTM Detection System (DakoCytomation, Glostrup, Denmark) according to manufacturer’s instructions. The characteristics
of antibodies are summarized in Table 1. Immunohistochem- ical stains showed that tumor cells were strongly positive for vimentin (Fig 3B) and anti-Müllerian hormone (AMH) (Fig 3C). Other antibodies including broad-spectrum cytokeratin AE1/AE3 (Fig 3D), inhibin-α, estrogen receptor (ER), pro- gesterone receptor (PR), luteinizing hormone receptor (LHR), neuron-specific enolase (NSE), S100, smooth muscle actin (SMA), and desmin reacted negatively (Table 1).
Fig 1. (A) Radiological image of left testicular tumor (arrows). (B) Ultrasonographical image of hyperechoic prostatic nodule (aster- isk). (C) Diff-Quick stained cytological image of fluid content in the central cystic structure of the prostate showing desquamated epi- thelial cells and neutrophils. (D) High magnification of figure C exhibiting bacterial colony (arrow). (E) Diff-Quick stained cytological image of urine sediment showing desquamated epithelial cells and neutrophils.
Fig 2. (A) On the cut surface of the left testis, a well circumscribed white round mass bulges from the tunica albuginea of the testis and shows multilobular appearance. (B-D) Histologically, the tumor mass is surrounded by fibroconnective tissue capsule and incom- pletely subdivided by thin fibroconnective tissue. Bar = 200μm (B). In high magnification, tumor cells are composed of round cells with large cytoplasmic vacuole that pushes the nucleus to the periphery, resembling a signet-ring cell. Bar = 100μm (C). Few pleo- morphic elongated spindle cells are observed in the periphery of the tumor lesion. Bar = 50μm (D). Hematoxylin and eosin stain.
80 Chul-Ho Park and Chang-Ho Son
Discussion
Some of typical SCTs have been documented to induce signs of hyperestrinism such as alopecia and gynecomastia (1). To the best of our knowledge, there is no report of its occurrence in lipid-rich SCTs. The present case with lipid- rich SCT showed typical hyperestrinism, confirming that lipid-rich SCTs can also induce hyperestrinism. It should be noted that excessive estrogenic stimulation secreted from SCTs can also induce squamous metaplasia of all acini in the prostate, making them vulnerable to bacterial infections (1).
The present case showed serum estrogen levels beyond the normal range and exudate with neutrophils, bacterial colo- nies, and desquamated keratinocytes in the prostate cyst, sug- gesting that lipid-rich SCT-induced hyperestrinism cause prostate squamous metaplasia and then purulent prostatitis.
Moreover, this affected prostate gland may act as a hotbed of
bacteria proliferation, which may spread bacteria to down- stream and upstream of prostate glands as seen as cystitis in this case.
This tumor is morphologically or immunehistochemically rather closer to some of lipid-rich SCTs, which are positive for vimentin and AMH (2,3). Like this case, some of typical and lipid-rich SCTs did not express either Inhibin-α or desmin or both (3). Based on these findings, this tumor was diagnosed as a canine lipid-rich SCT. In addition, canine Leydig cell tumors are known to express LHR and vimentin, whereas none of these antigens have been expressed in canine seminomas (11-13). These immunohistochemical reactions, as well as typical morphological characteristics of lipid-rich SCTS, indicate that vimentin-positive but LHR-negative lipid-rich SCT of this case differed from canine seminoma or Leydig cell tumor.
The present case shared characteristic cell morphology Fig 3. (A) Cytoplasmic vacuoles of lipid-rich tumor cells are negative for periodic acid-Schiff reaction. Bar = 50 μm. (B-D) Immu- nohistochemically, tumor cells are positive for vimentin (B) and anti-Müllerian hormone (C) but negative pancytokeratin (D). Bar = 50μm.
Table 1. Antibodies used in the present study and results of immunohistochemistry (IHC) stains of the tumor
Antibodies Type Clone Source Dilution IHC results
Cytokeratin Mouse Mab AE1/AE3 DakoCytomation, Glostrup, D.K. 1:100 -
Vimentin Mouse Mab 3B4 DakoCytomation, Glostrup, D.K. 1:100 +++
AMH Mouse Mab A-9 Santa Cruz Biotechnology, Santa Cruz, CA, U.S.A. 1:100 +++
Inhibin-α Rabbit PCab - Santa Cruz Biotechnology, Santa Cruz, CA, U.S.A. 1:100 -
ER Mouse Mab 1D5 DakoCytomation, Glostrup, D.K. 1:100 -
PR Mouse Mab PgR 636 DakoCytomation, Glostrup, D.K. 1:100 -
LHR Rabbit PCab - Santa Cruz Biotechnology, Santa Cruz, CA, U.S.A. 1:100 -
NSE Mouse Mab F3-1C4 Millipore, Billerica, MA, U.S.A. 1:100 -
S100 Rabbit PCab - DakoCytomation, Glostrup, D.K. 1:100 -
SMA Mouse Mab P62736 DakoCytomation, Glostrup, D.K. 1:100 -
Desmin Mouse Mab DE-R-11 Novocastra, Newcastle, U.K. 1:100 -
Abbreviations: AMH, anti-Müllerian hormone; ER, estrogen receptor; PR, progesterone receptor; LHR, luteinizing hormone receptor; NSE, neuron-specific enolase; SMA, smooth muscle actin; Mab, monoclonal antibody; PCab, polyclonal antibody.
Clinical, Morphological and Immunohistochemical Characteristics of Canine Lipid-Rich Sertoli Cell Tumor 81
with other known canine signet-ring cell tumors. Generally, signet-ring cell gastrointestinal carcinomas which produce mucin are positive for PAS reaction and react with antibody against broad-spectrum cytokeratin AE1/AE3 but not against vimentin (5,13,14). In contrast, the present tumor cells reacted with antibody against vimentin but not with PAS stain and cytokeratin AE1/3, aiding in differentiation from the gastroin- testinal signet-ring carcinomas. PAS-negative, lipid-rich signet- ring cell mammary gland carcinomas are known to be vimen- tin-negative but ER- and PR-positive (6,7). This is in con- trast to the present study where tumor cells were positive for vimentin and negative for ER and PR. S100- and NSE-posi- tive canine signet-ring cell melanomas could also be distin- guished from the present case which were negative for the markers (4). Moreover, clinical, radiological, and ultrasono- graphic examinations did not provide evidence that the pres- ent case could have metastasized from signet-ring cell gastrointestinal and mammary carcinomas, and melanomas.
Based on these findings, the present case is a completely dif- ferent tumor from canine signet-ring cell carcinomas or mel- anomas.
The present case also shared similar pathological and immunohistochemical characteristics with signet-ring stro- mal tumors (SRSTs) of the human testes. In accordance with findings of the present study, PAS-negative SRSTs of human testes reacted with antibody against vimentin, but not with other antibodies including those against cytokeratin AE1/A3, ER, PR, and inhibin-α (9,10). Human testicular SRSTs often show presence of large round cells with eccentric nuclei dis- playing a signet-ring morphology, and immunohistochemical findings are consistent with human Sertoli cell tumor; there- fore, they are hypothesized to be a specific variant of Sertoli cell tumor (9). Unlike canine SCTs, human testicular SRSTs are extremely rare, and tumor-associated feminizing paraneo- plastic syndromes have never been reported (9,10).
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