Neuroendocrine differentiation and neuroendocrine morphology as two different patterns in large-cell bronchial carcinomas: outcome after complete resection

BACKGROUND: In 1999, large-cell neuroendocrine carcinoma of the lung was introduced by the World Health Organization (WHO) as a new tumor entity in the group of non-small cell, epithelial tumors, a differentiated classification of neuroendocrine tumors of the lung not existing until this time. Scientific knowledge on prognosis and therapy of these tumors, especially between those with neuroendocrine morphology only and those showing additional expression of neuroendocrine markers, is fragmentary. In this analysis, we studied the clinical behavior and the prognosis of these two rare tumor entities. PATIENTS AND METHODS: The analysis comprises 12 patients of a total of 2053, who underwent thoracotomy for non small-cell lung carcinoma between 1997 and 2005 in the Department of Thoracic Surgery at the University Hospital of Freiburg. Clinical data, pathological examinations as well as complete follow-up were reviewed from large-cell carcinoma with neuroendocrine morphology only (n=4) and from large-cell carcinoma expressing neuroendocrine markers (n=8). RESULTS: The median survival of patients with neuroendocrine morphology was 30 months (11–96 months). In the patient group showing the expression of neuroendocrine markers, the median survival time was 20 months (2–26 months). Tumor recurrences occurred in the group with neuroendocrine morphology, without exception, in the form of distant metastases and in the group with neuroendocrine markers as intrapulmonary metastases. CONCLUSION: Large-cell neuroendocrine carcinomas of the lung show aggressive behavior with a poor prognosis. Expression of neuroendocrine markers markedly reduce tumor-free interval as well as survival and might influence the site of metastases

Can renal oncocytoma be distinguished from chromophobe renal cell carcinoma by the presence of fibrous capsule?

The most important differential diagnosis of chromophobe renal cell carcinoma (CRCC) is renal oncocytoma. Due to overlapping morphological characteristics of renal oncocytoma and CRCC, particularly its eosinophilic variant, making a correct diagnosis can be challenging. To date, no data are available on the presence of the tumor fibrous capsule as a diagnostic feature in differentiating these tumors. The main purpose of this study was to establish the presence and compare the thickness of the tumor fibrous capsule between two tumor groups. A total of 37 tumors--18 cases of CRCC (three eosinophilic and 15 classic) and 19 cases of renal oncocytoma--were analyzed. Four slides of each tumor stained with hematoxylin and eosin were first scanned at low-power magnification (x40) to assess the presence of the capsule. If present, the capsule was measured in three different thickest areas at higher magnification (x200). The mean value of capsule thickness was calculated and taken into consideration. The capsule was present in 12 (66.7%) cases of CRCCs and in only two (10.5%) cases of renal oncocytomas. Statistical analysis showed significant difference between the presence of fibrous capsule in these two observed tumor groups (P = 0.001). Average thickness of capsule in CRCCs was 337.7 microm, and 115.4 microm in renal oncocytomas, but the median was not statistically significant (P = 0.198). Studies with a larger number of cases are needed to conclude if this characteristic could be a low-cost, reliable microscopic feature in differentiating between CRCC and renal oncocytoma