Fine-needle aspiration cytology of metastatic clear-cell renal carcinoma presenting as a solitary mass in the head of the pancreas

Isolated Pancreatic Metastases of Renal Cell Carcinoma-Clinical Particularities and Seed and Soil Hypothesis

A meta-analysis of 1470 isolated pancreatic metastases of renal cell carcinoma revealed, that, in addition to the unusual exclusive occurrence of pancreatic metastases and the favourable treatment results, the isPMRCC is characterised by further peculiarities of the clinical course: The lack of prognostic significance of volume and growth rate dependent risk factors and the independence of treatment results from standard or local resections. As an explanation for all these peculiarities, according to today's knowledge, a strong acting seed and soil mechanism can serve, which allows embolized tumour cells to grow to metastases only in the pancreas, and prevents them definitively or for years in all other organs. The good prognosis affects not only isolated PM, but also multi-organ metastases of the RCC, in which the additional occurrence of PM is also associated with a better prognosis. Genetic studies revealed specific changes in cases of PM of RCC: Lack of loss of 9p21.3 and 14q31.2, which are otherwise specific gene mutations at the onset of generalization, a low weight genome instability index, i.e., high genetic stability, and a low rate of PAB1 and a high rate of BPRM1 alterations, which signal a more favourable course. The cause of pancreatic organotropism in isPMRCC is still unclear, so only those factors that have been identified as promoting organotropism in other, more frequent tumour entities can be presented: Formation of the pre-metastatic niche, chemokine receptor-ligand mechanism, ability to metabolic adaptation, and immune surveillance.

Isolated Pancreatic Metastases of Renal Cell Cancer: Genetics and Epigenetics of an Unusual Tumour Entity

Isolated pancreatic metastases of renal cell carcinoma (isPMRCC) are a rare manifestation of metastatic renal cell carcinoma (mRCC) characterized by two peculiarities: (1). The definite or at least long-term exclusive occurrence of metastases in the pancreas and (2). an unusual low tumour aggressiveness with slow tumour progression and consecutive, good treatment results. According to current knowledge, the exclusive occurrence of pancreatic metastases is due to a highly specific and highly selective seed and soil mechanism, which does not allow metastases settlement outside the pancreas, and whose detailed genetic/epigenetic causes are not yet elucidated. Recent studies have shed light on some of the pathways involved for the protracted course of the disease and highlighted a special genetic profile (lack of loss of 9p, lower weight genome instability index, low frequency of BAP1 alterations, and a high frequency of PBRM1 loss), which deviates from the conventional mRCC profile. Finally, the question of the reasons for the long-term relative genetic stability of the involved cell clones, which is an essential prerequisite for a favourable prognosis, remains unanswered.

Isolated Pancreatic Metastases of Renal Cell Carcinoma-A Paradigm of a Seed and Soil Mechanism: A Literature Analysis of 1,034 Observations

Previously documented arguments, in favor of the suspected impact of a seed and soil mechanism, in the development and progression of isolated pancreatic metastasis of renal cell carcinomas (isPM) are: (1) uniform and independent from the side of the primary tumor distribution of isPM within the pancreas and, (2) the similar survival rates for singular and multiple isPM. In addition, the present study adds new arguments that further confirm the importance of an seed and soil mechanism in isPM: (1) Within the singular isPM, the size of the metastasis does not affect the overall survival; (2) Within the group of multiple isPMs, the overall survival does not depend on the number of metastases; (3) For synchronous and metachronous isPM, survival rates are also not different, and (4) Within the group of metachronous isPM there is also no correlation between the overall survival and interval until metastases occurs. This unusual ineffectiveness of otherwise known risk factors of solid cancers can be explained plausibly by the hypothesis of a very selective seed and soil mechanism in isPM. It only allows embolized renal carcinoma cells in the pancreas to complete all steps required to grow into clinically manifest metastases. In all other organs, on the other hand, the body is able to eliminate the embolized tumor cells or at least put them into a dormant state for many years. This minimizes the risk of occult micrometastases in distant organs, which could later—after isPM treatment—grow into clinically manifest metastases, so that the prognosis of the isPM is only determined by an adequate therapy of the pancreatic foci, and prognostic factors, such as total tumor burden or interval until the occurrence of the isPM remain ineffective.

Observations on Solitary Versus Multiple Isolated Pancreatic Metastases of Renal Cell Carcinoma: Another Indication of a Seed and Soil Mechanism?

Isolated pancreas metastases are a rare type of metastasis of renal cell carcinoma, characterized by the presence of pancreatic metastases, while all other organs remain unaffected. In a previous study, we determined arguments from the literature which (a) indicate a systemic-haematogenic metastasis route (uniform distribution of the metastases across the pancreas and independence of the metastatic localization in the pancreas of the side of the renal carcinoma); and (b) postulate a high impact of a seed and soil mechanism (SSM) on isolated pancreatic metastasis of renal cell carcinoma (isPM) as an explanation for exclusive pancreatic metastases, despite a systemic haematogenous tumor cell embolization. The objective of the study presented was to search for further arguments in favor of an SSM with isPM. For that purpose, the factor's histology, grading, and singular/multiple pancreas metastases were analyzed on the basis of 814 observations published up to 2018. While histology and grading allowed for no conclusions regarding the importance of an SSM, the comparison of singular/multiple pancreas metastases produced arguments in favor of an SSM: 1. The multiple pancreas metastases observed in 38.1% prove that multiple tumor cell embolisms occur with isPM, the exclusive "maturation" of which in the pancreas requires an SSM; 2. The survival rates (SVR), which are consistent with singular and multiple pancreas metastases (despite the higher total tumor load with the latter), prove that the metastasized tumor cells are not able to survive in all other organs because of an SSM, which results in identical SVR when the pancreatic foci are treated adequately.

Isolated pancreatic metastases from renal cell carcinoma: an outcome of a special metastatic pathway or of specific tumor cell selection?

Isolated pancreatic metastases (isPM) are a rare metastasizing pattern in the natural history of renal cell cancer. Their clinical hallmark is that they are confined to a single organ, the pancreas, while all other organs are unaffected for a long time. Almost all workers in the field suggested that mechanical tumor cell propagation to the pancreas may be the mechanism underlying this metastasizing pattern. In 2006 our group, by contrast, proposed an alternative mechanism, i.e. a special affinity of the tumor cells for the pancreas. In the present study an attempt was made to shed more light on the settlement of isPM by reviewing recent literature data. 666 observations of isPM reported in the literature were reviewed. The analyses showed that local lymphatic spread does not play a major role because the lymphatic system is, in general, rarely involved in isPM. This also applies to a local venous spread, because the site of pancreatic metastases is independent of the side affected by the primary renal cancer. But the results are compatible with a systemic metastatic pathway. That metastases in other organs, which would be expected given a systemic spread, are absent can plausibly be explained by a seed and soil mechanism: only the pancreas offers the tumor cell emboli an environment which is conducive to the growth of clinically manifest metastases, while settlement of metastatic tumor cells is prevented in all other organs.

Cytology of the Pancreas: A Practical Review for Cytopathologists

Pancreatic cytopathology plays a critical role in the management of patients with cystic and solid pancreatic masses. The frequency of pancreatic fine-needle aspiration continues to increase and general surgical pathologists and cytopathologists need to be aware of the most commonly encountered entities as well as the pitfalls associated with gastrointestinal tract contaminants in endoscopic ultrasound-guided fine-needle aspiration. This article focuses on the most commonly encountered pancreatic lesions and the importance of correlation of cytologic features with clinical, radiologic, and ancillary studies for accurate diagnosis.

Isolated pancreatic metastasis of hepatocellular carcinoma after curative resection

Hepatocellular carcinoma (HCC) is a highly malignant tumor and extrahepatic metastasis is not rare. The most common organ of HCC metastasis is lung, followed by bone and adrenal gland. To the best of our knowledge, isolated pancreatic metastasis of HCC that developed after curative resection has not been described previously. We report a case of solitary pancreatic metastasis of HCC, which was found 28 mo after left hemihepatectomy for HCC. The lesion was successfully resected with the pancreas, and no other metastatic lesions have been found in follow-up.

Systematic review of pancreatic surgery for metastatic renal cell carcinoma

BACKGROUND

This study examined the clinical outcome of patients with pancreatic metastases from renal cell carcinoma (RCC).

METHODS

A systematic literature search produced individual data for 311 surgically and 73 non-surgically treated patients with pancreatic RCC metastases. A further ten patients underwent resection at the authors' institution.

RESULTS

In the resected group, pancreatic metastases were solitary in 65.3 per cent, symptomatic in 57.4 per cent, and were preceded and/or accompanied by extrapancreatic disease in 22.3 per cent. Respective values in the unresected group were 59, 60 and 58 per cent. Disease-free survival rates were 76.0 and 57.0 per cent respectively at 2 and 5 years after resection, and overall survival rates were 80.6 and 72.6 per cent. The only significant risk factor for disease-free survival after pancreatic resection was extrapancreatic disease (P = 0.001), and that for overall survival was symptomatic RCC metastasis (P = 0.031). Two- and 5-year overall survival rates were 41 and 14 per cent respectively in unresected patients.

CONCLUSION

The actuarial 5-year overall survival rate following pancreatic surgery for RCC metastases was 72.6 per cent, as determined by pooled analysis from published series. Extrapancreatic disease was an independent risk factor for recurrence, but had no significant impact on overall survival.

Solitary and multiple isolated metastases of clear cell renal carcinoma to the pancreas: an indication for pancreatic surgery

BACKGROUND

Isolated pancreatic metastases (isPMs) of clear cell renal carcinoma are rare. Most of them are solitary; some are multiple. The reported rates and the clinical implications of multiple isPMs from clear cell renal cancer vary. Therefore, the available literature was analyzed to shed light on the clinical significance of these extremely rare metastatic lesions.

METHODS

A literature search brought to light 236 cases of isPMs (both solitary and multiple) from renal cell carcinoma. These were analyzed.

RESULTS

A total of 12% of the metastases were synchronous with the primary tumor, and 88% were metachronous, occurring 10.0 +/- 6.5 years (mean +/- SD) after nephrectomy. A predilection for a specific part of the pancreas was not identifiable. The localization of the renal cell cancer (left or right kidney) did not have any effect on the site of the metastases. Seventy-four (39%) of the metastases to the pancreas were multiple (3.2 +/- 1.5). Their epidemiology did not differ from that of solitary metastatic lesions. Actuarial 3- and 5-year survival rates after radical resection were 78% and 78%, respectively, for multiple versus 75% and 64% for solitary metastases.

CONCLUSIONS

The epidemiological data do not support a direct local lymphogenous or venous spread from the primary tumor to the pancreas. They rather suggest a systemic spread. Because of the positive outcome, radical removal of both solitary and multiple metastases should be attempted in eligible patients.

Distribution of subtypes of metastatic renal-cell carcinoma: correlating findings of fine-needle aspiration biopsy and surgical pathology

Clear-cell (CRCC), papillary (PRCC), and chromophobe (CHRCC) renal-cell carcinoma (RCC) are the three most frequent subtypes of RCC. The rate and distribution of their metastatic lesions have not been well studied in cytopathological materials. Sixty-two fine-needle aspiration biopsy cases of metastatic RCC were studied and correlated with surgical pathology of RCCs with and without metastasis. Special stains for glycogen and immunostaining for cytokeratins, vimentin epithelial membrane antigen (EMA), and carcinoembryonic antigens, and electron microscopic studies were performed. Fifty-nine cases of CRCC and three of PRCC subtypes were retrieved from the cytopathology files at the Ottawa Hospital in a period of 10 years. Of these cases, 10 metastatic CRCC and one metastatic PRCC were diagnosed prior to the diagnosis of the primary tumor. CHRCC and sarcomatoid RCC were not represented in cytopathological specimens. CRCC displayed characteristic filmy cytoplasm and nuclei with prominent nucleoli. PRCC was characterized by dense cytoplasm, large nuclei with prominent nucleoli, and papillary architectures. In addition, all RCCs were characterized by the presence of glycogen and the absence of mucin by using histochemical techniques and electron microscopic studies and positive reactivity for cytokeratins (CK) and vimentin (VIM). In the same period, there were a total of 380 patients with RCC divided into 310 CRCCs, 55 PRCCs, and 15 CHRCCs associated with metastases in 142, 9, and 1 case, respectively. CRCC is by far the most common subtype found in metastases sampled in cytopathology. PRCC, CHRCC, and sarcomatoid RCC were underrepresented. Awareness of this propensity of RCC and the characteristic cytopathological, histochemical, immunohistochemical, and ultrastructural features are helpful in the diagnosis of metastatic RCC.

Renal cell carcinoma to the pancreas in surgical pathology material

BACKGROUND

Clear cell carcinomas of the pancreas are rare and more likely represent metastatic renal cell carcinoma (RCC).

METHODS

Twenty-one cases of metastatic RCC to the pancreas were retrieved from the files of the Endocrine Registry of the Armed Forces Institute of Pathology. Histologic features were reviewed, special stains and immunohistochemical studies were performed, and patient follow-up data were obtained.

RESULTS

The patients included 9 women and 12 men ages 47-76 years (mean, 64.4 years). Patients experienced weight loss, abdominal pain, or a mass lesion. The tumors occurred anywhere within the pancreas. The mean size of the tumors was 4.0 cm. Histologically, the tumors were comprised of clear cells with a rich vascular network. The RCC was diagnosed before (n = 17 patients; ages up to 32.7 years) or after (n = 4 patients; ages up to 13.2 years) the pancreatic metastases were discovered. Surgery was used in all patients. Adjuvant chemotherapy was used in 4 patients. From the date of the diagnosis of pancreatic metastasis, 13 patients were dead with disseminated disease (DD) (mean, 4.5 years), and 8 patients were without disease (mean, 9.0 years). From the date of the diagnosis of primary RCC, 13 patients were DD (mean, 12.7 years), and 8 patients were without disease (mean, 24.7 years).

CONCLUSIONS

Although histochemical and immunohistochemical studies may help in the distinction between patients with primary versus metastatic clear cell tumors of the pancreas, clinical confirmation should be obtained. Surgical resection of the pancreatic metastatic disease is suggested, because the patient may still have a prolonged survival.