[Kidney cancer in horseshoe kidney. A case report of an unexpected diagnosis]

"Man in Istanbul" Lesions of the Urinary Tract (Known Entities in an Unusual Context): Melanoma, Carcinoid Tumors, Epithelioid Angiosarcoma

Certain tumors are more difficult to recognize when they present in an unusual location. Within the urinary tract, primary melanomas, carcinoid tumors, or epithelioid angiosarcoma could present diagnostic challenges due to their infrequent occurrence. This article emphasizes the clinical and histopathologic features of these entities and their differential diagnoses including the immunophenotype and their prognoses.

Primary neuroendocrine tumors of the kidney: morphological and molecular alterations of an uncommon malignancy

Primary neuroendocrine (NE) tumors of the kidney (PNRTs) are rare and frequently mistaken for other renal and urothelial cancers. We evaluated morphological and molecular findings of 11 PNRTs classified according to the World Health Organization classification of lung NE tumors. Patients included 5 men and 6 women with a median age of 50 years. These tumors occurred in the left (5/11), right (3/11), and horseshoe (1/11) kidney. The histologic patterns were predominantly solid, trabecular, and pseudoglandular. Lymphovascular invasion and calcification were found in 3 and 1 cases, respectively. There were 2 atypical and 9 typical carcinoids. At the time of surgery, 2 patients with atypical carcinoids had hepatic metastasis, and 1 of the typical carcinoid patients had lymph node metastasis. All cases showed <1% proliferative rate, except 2 cases with hepatic metastasis, which showed 3% to 5% with MIB1/Ki-67 immunostaining. Immunostainings were frequently positive for synaptophysin, chromogranin, CD56, CD99, and neuron-specific enolase. Follow-up data (average 4 years) were available for 6 patients. Two patients with distant metastasis were alive with disease, and four patients with no metastasis were alive without disease. We evaluated the association of PNRT and loss of heterozygosity (LOH) on chromosome 3p21 and found LOH in 2 of 3 cases. However, the comparative genomic hybridization study (2/2) did not demonstrate significant chromosomal imbalances. We conclude that PNRTs are positive for NE markers and may have LOH on chromosome 3p21. PNRTs should be classified as NE tumors in other sites, and proliferative rate can be an indicator of aggressive behavior/metastasis.

Renal carcinoid tumor: a clinicopathologic study of 21 cases

Renal carcinoid tumors are exceedingly rare tumors that have been primarily documented as case reports in the literature. In this study, we report a series of 21 renal carcinoid tumors, with emphasis on histopathologic features and clinical outcomes. Patient age ranged from 27 to 78 years (average 52 y). The majority of specimens consisted of radical nephrectomies with or without associated lymph node dissection. Nine tumors were present in the left kidney and 10 were present in the right; location was not available for 2 specimens. No anatomic region of the kidney appeared to be preferentially involved. Twenty tumors were unifocal and ranged in size from 2.6 to 17 cm (average 6.4 cm), and 1 tumor presented as 2 nodules measuring 1 and 2.8 cm. Four patients had a documented history of a horseshoe kidney. Two patients had a history of renal calculi and 1 patient had a history of urothelial carcinoma 8 years prior. Presenting symptoms and clinical findings included back or flank pain (n=6/9), enlarging abdominal mass or fullness (n=2/9), hematuria (n=2/9), and anemia (n=1/9). Twelve patients had concurrent metastases at the time of initial surgery to sites including lymph nodes (n=11/12), liver (n=5/12), bone (n=1/12), and lung (n=1/12). One additional patient developed subsequent metastases to the liver within 6 months of surgery. Examination of the specimens identified carcinoid tumor with a variety of patterns including tightly packed cords and trabeculae with minimal stroma (n=17/21), trabecular growth with prominent stroma (n=4/21), focal solid nests (n=4/21), focal glandlike lumina (n=4/21). The border between tumor and normal kidney was sharply defined in most cases (n=16/21), although focal infiltration was noted in 5/21 cases. Extracapsular extension was documented in 11/21 (52%) cases. Calcifications were present in 5/21 cases. Mitotic activity, measured as mitoses per 10 high-power fields, ranged from 0 to 2 in most cases, with 1 case demonstrating up to 4 mitotic figures per single high-power field. Necrosis was absent in all cases. Immunostains were frequently positive for synaptophysin (n=18/20), chromogranin (n=13/20), Cam5.2 (n=14/16), and vimentin (n=12/15). CK7 was focally positive in a small subset of cases (n=3/18) and CK20 was positive in 1 case. TTF-1 and WT-1 were negative in all cases examined. Clinical follow-up was available on 15 patients and ranged from 3 months to 11 years. One patient died of disease at 8 months after surgery and 1 patient died without disease at 11 years after surgery. Of the remaining patients, 7 patients were alive without disease and 6 patients were alive with disease. Additional metastases developed in 4 patients and included metastases to the liver and bone.