RENAL ONCOCYTOMA

Up to date only five cases of renal oncocytomas have been reported in Japan. We describe two cases of renal oncocytomas. Case 1: A 63-year-old woman, who had no urological symptoms, was pointed out of a cystic mass in the left kidney by chance. A resected kidney had a cystic tumor, which was well encapsulated and measured 6 v 7 times 8 cm. The tumor was unilocular and thick-walled cyst filled with bloody fluid. Histologically, the tumor was composed of oncocytes with eosinophilic granular cytoplasms that were packed with mitochondria. Case 2: A 70-year-old woman died of malignant lymphoma and an autopsy was performed. The tumor was found in the right kidney by chance and measured 1 cm in diameter. The cut-surface of the tumor was uniform and tan-brown in color. Histologically, the tumor was composed of cells same as Case 1. We discuss the incidence of this tumor and the morphological characteristics of our cases. ACTA PATHOL. JPN. 36: 1377 -1382, 1986.     

Cystic hamartoma of the renal pelvis: a rare pathologic entity.

We report a case of a rare cystic renal tumor previously termed cystic hamartoma of the renal pelvis. A 53-year-old woman presented to her gynecologist with menometorrhagia. She subsequently had a computed tomographic scan that demonstrated an incidental cystic mass in the lower pole of the left kidney. Histologically, the tumor was composed of a mixture of benign mesenchymal and epithelial components. The stroma consisted of spindle cells with monomorphic nuclei and abundant eosinophilic cytoplasm that resembled smooth muscle and that reacted positively with antibodies to alpha-smooth muscle actin, desmin, and vimentin. The epithelial component was composed mostly of cysts lined by cuboidal-to-columnar epithelium. Focal dilated cysts were lined by epithelium with oncocytic features. We think that this entity is distinct from other renal tumors, including mesoblastic nephroma, cystic nephroma, or a cystic, partially differentiated nephroblastoma, and that it is best classified as a cystic hamartoma of the renal pelvis.     

Coexistence of mature teratoma and thecoma in an ovary. A report of two cases.

Two cases of coexisting mature teratoma and thecoma are reported. In Case 1, a 36-year-old woman presented with severe genital bleeding and an ovarian tumor, 12 x 9 cm in size, was found. In Case 2, a 48-year-old postmenopausal woman presented with severe lower abdominal pain and an ovarian tumor, 15 x 11 cm in size, was detected. Macroscopically, the resected tumors of both cases showed a unilocular cystic tumor adjacent to a solid tumor. Microscopically, the cystic tumors were composed of cutaneous tissues and the solid tumors consisted of spindle cells with lipid-rich cytoplasm, arranged in interlacing bundles. The cystic tumor and the solid tumor were completely separate and no transitional features were recognized histologically.     

Mixed epithelial and stromal tumor of kidney with malignant transformation: report of two cases and review of literature

We present 2 cases of mixed epithelial and stromal tumor of the kidney with sarcomatous transformation. One patient was a 53-year-old woman who presented with macroscopic hematuria. The resected tumor involved the right renal parenchyma, measuring 13.0 x 8.0 x 4.0 cm, and extended to perirenal adipose tissue. The second patient was a 56-year-old woman who presented with right flank colic pain. The tumor measured 6.0 x 5.5 x 4.0 cm, with an intact capsule at the upper pole. Both tumors showed a well-circumscribed, multilocular, cystic, and focally solid mass. Sections of both tumors revealed benign and malignant components. The benign component consisted of multilocular cysts and fibrous stroma with a focally ovarian stromalike component. The malignant component in both cases was predominantly composed of undifferentiated cellular spindle cell sarcoma with frequent mitoses. One case showed additional heterologous malignant elements, including rhabdomyosarcomatous, chondrosarcomatous, and focal carcinomatous components. We report 2 additional cases of sarcomatous transformation in mixed epithelial and stromal tumor of the kidney.     

Concurrent angiomyolipoma and two oncocytomas in the same kidney

We report on a rare case of synchronous angiomyolipoma (AML) and 2 oncocytomas (OCs) in the same kidney of a 73-year-old woman. During the course of a follow-up for a long-standing staghorn calculus in the left kidney, a 4-cm right suprarenal mass and a small solid nodule adjacent to a cyst in the midportion of the right kidney were radiographically discovered. A radical nephrectomy was performed. The suprarenal tumor was found to be an AML, and the small nodule was an OC (1.5 cm). An additional OC (0.8 cm) elsewhere in the right kidney was also identified. The coexistence of AML and other renal tumors is uncommon. Among reported cases, conventional renal cell carcinoma, possibly reflecting its higher incidence, has been the most common concurrent tumor with AML. Although only rare cases of simultaneous AML and OC have been reported in the literature, it appears that the proportion of OC among concurrent renal tumors with AML is higher than expected based on its frequency among all surgically resected renal neoplasms. Whether there is a pathogenetic association between AML and OC needs to be further investigated.     

Coexistence of Mature Teratoma and Thecoma in an Ovary

Two cases of coexisting mature teratoma and thecoma are reported. In Case 1, a 36 year old woman presented with severe genital bleeding and an ovarian tumor, 12x9 cm in size, was found. In Case 2, a 48-year-old postmenopausal woman presented with severe lower abdominal pain and an ovarian tumor, 15x11 cm in size, was detected. Macro-scopically, the resected tumors of both cases showed a unilocular cystic tumor adjacent to a solid tumor. Microscopically, the cystic tumors were composed of cutaneous tissues and the solid tumors consisted of spindle cells with lipid rich cytoplasm, arranged in interlacing bundles. The cystic tumor and the solid tumor were completely separate and no transitional features were recognized histologically. Acta Pathol Jpn 41: 922-926, 1991.     

Anastomosing hemangioma of the kidney: a case report of a rare subtype of hemangioma mimicking angiosarcoma and review of the literature

Anastomosing hemangioma is a recently described, unusual variant of capillary hemangioma which seems to be unique for the genitourinary system, with a particular proclivity for the kidney. Histologically, it is characterized by a unique sinusoidal architecture reminiscent of splenic parenchyma that can lead to concern for angiosarcoma. We herein report a further case of anastomosing hemangioma originating in the right kidney of a 48-year-old Chinese man. The patient had a past medical history significant for hepatocellular carcinoma; this tumor was incidentally identified as an asymptomatic right renal mass during the periodical surveillance of the hepatic cancer. The resected tumor measured 2.5cm in maximum diameter and microscopically demonstrated an overall lobulated growth pattern with alternating cellular areas composed of anastomosing sinusoidal capillary-sized vessels lined by hobnail endothelial cells, and edematous, hyaline paucicellular areas. Cytologically the tumor cells were generally bland and exhibited positivity for CD31, CD34 immunohistochemically. The patient had been in a good status without evidence of tumor recurrence 12 months after the surgery. This rare variant renal hemangioma is in need of more recognition and should not be over-diagnosed as a malignance, particularly angiosarcoma.     

Malignant rhabdoid tumor arising in a mixed epithelial,stromal tumor of kidney: report of a male case,review of the literature

Mixed epithelial and stromal tumor (MEST) of the kidney is a rare biphasic tumor composed of both stromal and epithelial components, the latter showing a variable proportion of solid to cystic areas. These tumors show a marked female predominance, commonly occur in perimenopausal age groups, and often have an ovarian-type stroma with ER and PR positivity, suggesting steroids may play a role in pathogenesis. Although typically benign, rare cases showing malignant transformation have been reported. We present a case of a 42-year-old man with a 10 cm right kidney mass located in the renal pelvis. Histologically, the majority of the tumor was composed of a diffuse, sheet-like growth of malignant cells demonstrating a rhabdoid morphology with large nuclei, prominent nucleoli, and eosinophilic eccentric cytoplasm. Brisk mitotic activity and coagulative type necrosis was also noted. Intimately associated with this malignant rhabdoid component was a much smaller portion of tumor featuring variably sized bland epithelial tubules embedded within a stroma composed of bland spindle cells and areas of hyalinization, diagnostic of MEST. By immunohistochemistry, the malignant rhabdoid tumor portion of the neoplasm showed complete loss of nuclear INI-1, while the MEST component retained nuclear expression of this antigen. With these features taken together, our case represents a malignant rhabdoid tumor arising in a background of MEST. To our knowledge, this case represents the first case of a MEST showing malignant transformation in the form of malignant rhabdoid tumor in a male patient in the English language literature.     

Peritoneal endometriosis in the broad ligament presenting as a large tumor

Peritoneal endometriosis presenting as a tumor is very rare. A case of peritoneal endometriosis in the broad ligament presenting as a large tumor is reported. A 39-year-old woman had a solid and cystic tumor with many microcysts, measuring 17 x 13 x 3.5 cm, mainly located in the right posterior broad ligament. Histologically, the tumor consisted of many endometrial glands associated with various amounts of endometrial stroma. Neither the glands nor the stromal cells had cellular atypia. We diagnosed peritoneal endometriosis presenting as a tumor. Among the six cases (five previously reported cases and our case) of tumor-like endometriosis in the peritoneum, two cases (33%) had received tamoxifen therapy and four cases (67%) had cystic or solid and cystic tumor. Among them, the tumor size ranged from 3 to 17 cm in diameter, and our case was the largest. In conclusion, this case is rare, but it is important for pathologists to be aware of the phenomenon (that extensive peritoneal endometriosis produces a large tumor) in the histological diagnosis of a tumor in the peritoneum.     

MALIGNANT BRENNER TUMOR -A CASE REPORT

A 55-year-old female had a partly cystic, partially solid tumor of the left ovary. Histologically, the tumor revealed typical benign features of Brenner tumor mixed with malignant areas showing large epithelial nests composed of marked pleomorphic cells. Only 4 cases of malignant Brenner tumor have been reported including ours to our knowledge in Japan.     

Uterine adenomyoma with uterus-like features: a report of two cases

Two uterine adenomyomas with unusual features are presented. Case 1 was a 43-year-old woman who had a 1-year history of menorrhagia and dysmenorrhea. The uterus showed a 3-cm-sized mass attached to the posterior wall of the lower uterine segment. On section, there was a well-circumscribed, submucosal cystic mass with a thick muscular wall. Histologically, the cavities were lined by well-developed secretory-phase endometrium and surrounded by smooth muscle, like a small uterus. Case 2 was a 52-year-old woman who visited the hospital because of itching sensation on the vulva. On physical examination, the mass was found on the left side of the pelvis. The enlarged uterus had an 8-cm-sized protruding mass from the left side of the lower uterine segment. On section, the mass was cystic and solid. Histologically, the cysts were lined by thin basalis-type endometrial glands and stroma, and the solid portion was composed of smooth muscle and fat cells.     

Pigmented microcystic chromophobe renal cell carcinoma

We report a case of a 60-year-old female with a pigmented microcystic chromophobe renal cell carcinoma (PMCRCC). The tumor was 4.5cm in diameter, and was located in the right kidney. Grossly, on cross section, the tumor was light gray with multiple small brown to black pigmented foci up to 0.2cm in diameter. Histologically, the tumor showed a microcystic arrangement with cribriform areas and formation of adenomatous structures. The microcystic and cribriform areas were composed of larger pale cells and smaller eosinophilic cells, with cytological features of conventional chromophobe renal cell carcinoma (CRCC). The cytological features of the cells within the adenomatous structures were different. These cells were mostly columnar with nuclei at the base, and had a variable amount of pale to eosinophilic cytoplasm. There were foci of ample brown pigmentation located in the cytoplasm of the tumor cells and extracellularly. In addition, microscopic calcifications were present. Immunohistochemically, the tumor cells were positive for EMA, E-cadherin, cytokeratin CAM5.2, and cytokeratin AE1/AE3. Cytokeratin 7 was positive only focally. S-100 protein, melan A, HMB 45, vimentin, and CD117 were negative. PMCRCC is a rare tumor. To the best of our knowledge, only one series containing 20 cases of this variant of CRCC has been described to date. The important feature is that PMCRCC seems to have a relatively benign biological behavior, and distant metastases and sarcomatoid transformation are absent.     

Concurrent primary carcinoid tumor arising within mature teratoma and clear cell renal cell carcinoma in the horseshoe kidney: report of a rare case and review of the literature

Primary carcinoid tumor arising in a mature teratoma of the horseshoe kidney is exceptionally rare and only 4 such cases have been reported in the world literature to date. The simultaneous occurrence of different subtypes of renal cell carcinoma (RCC) or RCC coexistence with non-RCC neoplasms from the same kidney is unusual and infrequently reported. Herein we report a case of primary carcinoid tumor arising within mature teratoma, concurrent with a clear cell RCC in the horseshoe kidney of a 37-year-old man. Histologically, both the carcinoid tumor and clear cell RCC demonstrated the characteristic morphology in their classic forms. In addition to the carcinoid tumor, the mature teratoma consisted of variably sized, large cystic spaces lined by cytologically bland mucinous columnar epithelium, pseudostratified columnar epithelium, ciliated epithelium and mature smooth muscle fibers were also identified within the cystic wall. Furthermore, foci of round, small nodules composed of mature prostatic acinus were noted in the teratoma which was confirmed by exhibiting strong immunoreactivity for prostate specific antigen. The present case serves to expand the histologic component that may be encountered in the mature terotoma of the kidney and further broadens the spectrum of primary tumors occurring in the horseshoe kidney.     

Renal epithelioid angiomyolipoma--a close mimic of renal cell carcinoma. Report of a case and review of the literature

The epithelioid variant of angiomyolipoma (EAML) is a rare tumor of unpredictable behavior that is composed of epithelioid, spindle, and giant cells and contains no or only a minimal amount of lipomatous tissue. The picture can lead to an erroneous diagnosis of renal cell carcinoma or sarcoma. We report on a case of EAML in the kidney of a 47-year-old female without any signs of tuberous sclerosis and review the literature. Grossly, a well-demarcated, spheroid, largely hemorrhagic tumor measuring 4.2 cm in diameter occupied the central third of the kidney. Histologically, it was solid, highly cellular, with occasional microcysts, composed of medium to large epithelioid cells with clear or oxyphilic cytoplasm, short spindle cells, and numerous giant multinucleated cells. After extensive sampling, adult-appearing fat tissue was found to present as rare foci of microscopic dimensions. Immunohistochemically, the tumor cells showed positive reactions with antibodies against HMB-45, melan A, CD-68, muscle-specific actin, and, rarely, smooth muscle actin. Cytokeratins and epithelial membrane antigen were negative. The EAML is a variant growing in a carcinoma-like pattern that can lead to an erroneous diagnosis of renal cell carcinoma. An extensive sampling and HMB-45 and CD-68 positivity combined with cytokeratin negativity are of paramount importance for the correct diagnosis. As a sporadic renal tumor it followed a benign course in most of the reported cases.     

Intrarenal epidermal cyst

An epidermal cyst is a very unusual cause of a renal mass, with only three cases reported in English literature. The authors report a case of this in a 51-year-old man with left flank pain and hematuria. A 5 x 4 cm-sized cystic mass, having an irregular margin with stippled calcification, was identified in the lower pole of the left kidney. A retroperitoneal laparoscopic simple nephrectomy was performed under the assumption that it was a renal tumor. Histologically, the tumor was identical in appearance to an epidermal cyst within the skin. Aberrant ectodermal implantation during embryogenesis has been postulated as a histogenesis of intrarenal epidermal cyst. However, the present case had a history of renal stone, which was treated with extracorporeal shock wave lithotripsy. Therefore, the authors suspected the pathogenetic mechanism of this lesion was a metaplasia of traumatic origin. The diagnosis of an epidermal cyst was not made preoperatively in the present case, or in the cases described in the literature. This diagnosis should be included in the differentiation of calcified intrarenal masses.     

Primary carcinoid tumor arising in a mature teratoma of the kidney: a case report and review of the literature

Primary carcinoid tumor, especially that arising in a mature teratoma of the kidney, is extremely rare; only 3 cases have been reported in the world literature to date. Because of the rarity of the lesion, its histogenesis and prognosis are unknown. We report a case of primary renal carcinoid tumor occurring in a mature teratoma in a 30-year-old woman. A computed tomographic scan of the abdomen revealed a mass in the left kidney containing dense calcification with minimal contrast enhancement. Histologically, the tumor was composed of trabecular and anastomosing ribbonlike nests, identical to the features of carcinoid tumors of other sites. Immunohistochemical stainings were positive for cytokeratin, neuron-specific enolase, and chromogranin. In addition, there were mature teratoid tissues, such as columnar epithelium, smooth muscle, and bone. The carcinoid tumor was under and closely apposed to the lining of the cysts. The patient did not have clinical manifestations of the carcinoid syndrome and had an uneventful recovery.     

Intrarenal mature cystic teratoma associated with renal dysplasia: case report and literature review

We report a case of intrarenal teratoma in a 6-year-old boy. Two years before his operation, multicystic masses had been found in the left side of his abdomen. In the operation, three main cystic masses were located in the upper and lower poles of the left kidney, which were removed in pieces. Histologically, the cyst wall was lined mainly with keratinizing squamous epithelium with hair follicles, shafts and sebaceous glands. The adjacent renal parenchyma showed atrophy, with partially dysplastic and angiomyolipoma-like lesions. Based on these findings, the lesion was diagnosed as mature cystic teratoma of dermoid cyst type. Extragonadal teratoma occurs predominantly along the median line of the body. Intrarenal teratoma is extremely rare; however, it should be distinguished from teratoid Wilms' tumor and other renal cystic lesions.     

Primary collision tumors of the kidney composed of oncocytoma and papillary renal cell carcinoma: A review

BackgroundThere are well known cases of hybrid tumors of chromophobe renal cell carcinoma (RCC) and oncocytoma in kidney, where both tumors have the same cell of origin – intercalated cell of the collecting duct. However, collision tumors composed of neoplasms originating from different cell lineages such as oncocytoma and papillary RCC are extremely rare. Herein, we made a collective literature review of reported cases of collision tumors composed of oncocytoma and papillary RCC, adding a case that we recently experienced.Material and methodsA PubMed database was search for collision tumors of the kidney composed of oncocytoma and papillary RCC and a collective literature review was made. To this cohort, we also added a recently encountered case with similar, confirmed by immunohistochemistry, morphological features.ResultsTo date 8 cases of a collision tumor composed of papillary RCC and oncocytoma have been described in the literature. All of them had a smaller papillary RCC component present within a larger oncocytoma.ConclusionBecause of a few cases of such a collision tumors reported, it is difficult to make classification and right clinical management of these patients. None of the reported cases had tumor recurrence or progression on a follow-up. The presence of only small portion of papillary RCC in a large oncocytoma raises a possibility of under-sampling of malignant component in large oncocytomas in core biopsy or surgically resected specimens. We recommend better sampling, particularly at the periphery of otherwise classic oncocytomas to unveil this possible association.