Renal cell carcinoma (RCC) is an important contributor to cancer-specific mortality worldwide. Targeted agents that inhibit key subtype-specific signaling pathways have improved survival times and have recently become part of the standard of care for this disease. Accurately diagnosing and classifying RCC on the basis of tumor histology is thus critical. RCC has been traditionally divided into clear-cell and non-clear-cell categories, with papillary RCC forming the most common subtype of non-clear-cell RCC. Renal neoplasms with overlapping histologies, such as tumors with mixed clear-cell and papillary features and hybrid renal oncocytic tumors, are increasingly seen in contemporary practice and present a diagnostic challenge with important therapeutic implications. In this review, we discuss the histologic, immunohisto-chemical, cytogenetic, and clinicopathologic aspects of these differential diagnoses and illustrate how the classification of RCC has evolved to integrate both the tumor's microscopic appearance and its molecular fingerprint.
Biopsy, Large-Core Needle ; Carcinoma, Renal Cell ; classification ; diagnosis ; genetics ; pathology ; DNA Copy Number Variations ; DNA, Neoplasm ; genetics ; Diagnosis, Differential ; Humans ; Kidney Neoplasms ; classification ; diagnosis ; genetics ; pathology

We report the case of a 67-year-old female who presented with a large renal mass. Gross examination of the nephrectomy specimen demonstrated a 6-cm renal mass that invaded into the renal sinus and perinephric fat. Histologic examination revealed two distinct tumor types. The first type was a conventional (clear cell) renal cell carcinoma that was of low nuclear grade and comprised the minority of the overall tumor. The second type was a high-grade collecting duct carcinoma with glandular/tubular differentiation and composed the majority of the tumor. Immunohistochemical studies demonstrated distinctive patterns of the two tumor types, thus confirming two distinct lineages. Five months postoperatively, the patient developed metastasis to the lungs and right hilar lymph node region. A fine needle aspiration of a lung nodule demonstrated a metastatic, poorly differentiated carcinoma, similar to the collecting duct carcinoma component in the kidney. Collision tumors of the kidney are rare with fewer than 10 cases reported in the literature. Our report further expands the spectrum of this rare phenomenon.
Aged ; Biopsy, Fine-Needle ; Carcinoma, Renal Cell ; pathology ; Female ; Follow-Up Studies ; Humans ; Kidney Neoplasms ; Lung Neoplasms ; secondary ; Lymphoma ; Mixed Tumor, Malignant

Background/Aims: In patients undergoing endoscopic retrograde cholangiopancreatography (ERCP), calcineurin activates zymogen, which results in pancreatitis. In this study, we aimed to determine the efficacy of tacrolimus, a calcineurin inhibitor, in preventing post-ERCP pancreatitis (PEP). Methods: This was a prospective pilot study in which patients who underwent ERCP received tacrolimus (4 mg in two divided doses); this was the Tac group. A contemporaneous cohort of patients was included as a control group. All patients were followed-up for PEP. PEP was characterized by worsening abdominal pain with an acute onset, elevated pancreatic enzymes, and a duration of hospital stay of more than 48 hours. Serum tacrolimus levels were measured immediately before the procedure in the Tac group. Results: There were no differences in the baseline characteristics between the Tac group (n=48) and the control group (n=51). Only four out of 48 patients (8.3%) had PEP in the Tac group compared to eight out of 51 patients (15.7%) who had PEP in the control group. The mean trough tacrolimus level in patients who developed PEP was significantly lower (p<0.05). Conclusions Oral tacrolimus at a cumulative dose of 4 mg safely prevents PEP. Further randomized controlled studies are warranted to establish the role of tacrolimus in this context.