Spontaneous regression of renal cell carcinoma: a pitfall in diagnosis of renal lesions

Complete spontaneous regression of a primary renal cell carcinoma. Report of a pathological proven case and review of the literature

Regression of primary renal cell carcinoma (RCC) is a rare phenomenon and for several reasons many of the reported cases have been questioned. We present a case that can be considered a true spontaneous and complete regression of a primary RCC. A 79-year-old female underwent nephrectomy because a renal tumor. At the time of surgery image studies showed a small para-aortic lymph node. The tumor measured 3cm and was analyzed completely. Histology showed a fibro-inflammatory lesion with necrosis, foamy macrophages and inflammatory cells. No neoplastic cells were observed and the lesion was interpreted as a localized type of xanthogranulomatous pyelonephritis. One year later a CT control scan, showed that the para-aortic lymph node had increased in size to 4cm. Fine needle aspiration revealed features of clear RCC. Metastatic dissemination was limited so surgical removal of the para-aortic lymph node was performed and the cytologic diagnosis confirmed.

Desmoid-type fibromatosis of the lower extremity: A unique case of complete lesion resolution following core needle biopsy

Desmoid-type fibromatosis (DF) is a rare neoplasm characterized by fibroblastic and myofibroblastic proliferation. While characterized as a benign lesion that does not metastasize, desmoid-type fibromatosis exhibits a wide range of behavior from aggressive local tissue invasion and post-surgical recurrence to spontaneous regression. Tumor regression can occur following systemic medical therapy or rarely may occur in the absence of therapy. We present a case of a 50-year-old female with a left thigh vastus medialis intramuscular mass which underwent imaging work-up and subsequent core needle ultrasound-guided biopsy showing results of desmoid-type fibromatosis. Following biopsy, the tumor showed prompt, complete regression with complete MRI resolution 2 months following biopsy. The patient showed no evidence of disease recurrence out to one year on MRI surveillance. This case report will discuss desmoid-type fibromatosis imaging features, treatment strategies, spectrum of disease behavior, and atypical behavior such as the spontaneous tumor regression as seen in this case report. To our knowledge there have been no reported cases of DF spontaneous regression 2 months following a core needle biopsy. Understanding the variable behavior of desmoid-type fibromatosis can assist the radiologist in guiding management of these lesions with the goal of optimizing clinical outcomes and preventing unnecessary aggressive treatments for stable or regressing disease.

Spontaneous regression of renal cell carcinoma: Reality or myth?

Spontaneous regression of a malignant tumor is a very rare phenomenon. Renal cell carcinoma (RCC) is an aggressive malignancy with an often unpredictable behaviour. The incidence of spontaneous regression in metastatic RCC has been estimated to lie between < 1% and 7%. The spontaneous regression of a primary RCC has been reported much less commonly. Our literature review assesses the published literature concerning spontaneous regression of either primary or metastatic RCC. In order to examine this phenomenon in more detail we performed a literature search in the PubMed Database using the Keywords “renal cell carcinoma”, “metastatic disease”, and “spontaneous regression” and included reports from the last 100 years. The incidence of spontaneous regressions in RCC has always been considered a special feature of RCC compared to other solid malignancies. The majority of case reports of spontaneously regressed RCC describe the regression of metastases after nephrectomy rather than the spontaneous regression of a primary tumor. In cases of reported regression of metastatic RCC, this mostly applied to pulmonary lesions. As possible reasons for spontaneous regressions host immune defense mechanisms against metastatic RCC tissue following nephrectomy are discussed as important factor. RCC is known to be highly immunogenic and the possible existence of cytotoxic serum factors and tumor-specific surface antigens may trigger a cell-mediated cytotoxicity as an immunological basis for regression. Histological verification of supposed regression of a primary tumor may cause diagnostic difficulties, since large central areas of necrosis and cystic lesions of the tumor can occur simultaneously. The well-known phenomenon of necrosis in a fast growing RCC at the time of nephrectomy must not be confused with true spontaneous regression. Therefore, in our opinion such reported cases of supposed partial spontaneous regressions of primary RCCs are highly questionable. Most cases of spontaneous regression of RCC metastases have been reported after nephrectomy as the only treatment. Debulking by tumor nephrectomy then gives the immune system the chance to cope effectively with the remaining much lower quantity of tumour antigens. However, the mechanisms leading to spontaneous regression of metastatic lesions after cytoreductive nephrectomy are still poorly understood.

Clinicopathologic outcomes of cystic renal cell carcinoma

BACKGROUND

The purpose of this study was to describe the clinicopathologic characteristics and oncologic outcomes of patients who underwent nephrectomy for cystic renal masses.

PATIENTS AND METHODS

Using an institutional review board-approved database, we retrospectively reviewed the clinical, pathologic, radiologic, and oncologic outcome data of patients who received nephrectomy for a complex cystic renal mass.

RESULTS

Sixty-one patients were identified who received nephrectomy for a complex cystic lesion. Average age was 64 years. Thirty-nine (64%) patients were male. At the time of resection, 1 (1.6%), 3 (4.8%), 53 (86.8%), and 4 (6.5%) had a Bosniak category II, IIF, III, and IV cystic lesion, respectively. Nineteen (31.1%) patients were initially managed expectantly but underwent surgery because of progression of complexity on follow-up. Mean pathologic tumor size was 3.3 cm (range, 0.7-12 cm). Forty-eight (78.6%) of the lesions were found to be malignant. Thirty-seven (77.1%), 5 (10.4%), 4 (8.3%), and 2 (4.1%) were stage T1a, T1b, T2a, and T3a, respectively. Clear cell was the most common histologic subtype (44%), followed by papillary (21.3%), and unclassified RCC (4.9%). With a mean and median follow-up of 48.4 and 43.0 months, respectively, no patients developed a local or metastatic recurrence. All patients were alive at last follow-up.

CONCLUSION

In our series with moderate follow-up, cystic RCCs do not appear to recur or progress regardless of size, histologic subtype, or grade. These findings suggest the malignant potential of cRCCs is significantly less than solid RCCs. Further investigation is required to determine if cRCCs should be classified and managed independently from solid RCCs.

Spontaneous tumour regression in keratoacanthomas is driven by Wnt/retinoic acid signalling cross-talk

A fundamental goal in cancer biology is to identify the cells and signalling pathways that are keys to induce tumour regression. Here we use a spontaneously self-regressing tumour, cutaneous keratoacanthoma (KAs), to identify physiological mechanisms that drive tumour regression. By using a mouse model system that recapitulates the behaviour of human KAs, we show that self-regressing tumours shift their balance to a differentiation programme during regression. Furthermore, we demonstrate that developmental programs utilized for skin hair follicle regeneration, such as Wnt, are hijacked to sustain tumour growth and that the retinoic acid (RA) signalling pathway promotes tumour regression by inhibiting Wnt signalling. Finally, we find that RA signalling can induce regression of malignant tumours that do not normally spontaneously regress, such as squamous cell carcinomas. These findings provide new insights into the physiological mechanisms of tumour regression and suggest therapeutic strategies to induce tumour regression.

Spontaneous regression of metastatic pulmonary renal cell carcinoma in the setting of sarcomatoid differentiation of the primary tumour

We present a case of spontaneous regression of pulmonary metastases from renal cell carcinoma (RCC) with sarcomatoid differentiation, prior to intervention. The patient presented with conventional type RCC with Furhman Grade 4/4 and sarcomatoid differentiation, complicated by pulmonary metastases. Palliative systemic therapy was planned, but prior to the onset of treatment, serial computed tomography scans demonstrated regression of metastatic disease. Spontaneous regression of metastases is rare, but well-documented in conventional clear cell RCC. To the best of our knowledge, this has not previously been described in the setting of sarcomatoid differentiation of the primary tumour.

Spontaneous regression of renal cell carcinoma

Renal cell carcinoma (RCC) comprises 3-4% of all malignant tumours among adults in Poland. Spontaneous regression of RCC is a rare but well-known phenomenon. Its frequency is estimated to be approximately 1% and a large part of the percentage is accounted for by the regression of pulmonary metastases in the course of clear type of RCC treatment. We searched PubMed, Embase and SciVerse Scopus databases, identifying 59 case reports of spontaneous regression of RCC. Those medical histories come from reports from around the world and date back up to 40 years. This review includes their analysis as well as description of possible explanations of this phenomenon postulated by different authors, including both misdiagnosis and immunological reactions. This study indicates that reliable diagnostics and reporting of all the cases of spontaneous regression play a key role, as this is the only method which enables a better perspective in understanding this issue.

Low-grade clear cell renal cell carcinoma mimicking hemangioma of the kidney: a series of 4 cases

CONTEXT

Clear cell renal cell carcinoma (CCRCC) has a rich, sinusoid-like vascularity frequently used as a diagnostic criterion. CCRCC with predominantly vascular architecture has not been described.

OBJECTIVE

To describe 4 unusual CCRCC cases, primarily presenting with hemangioma-like morphologic pattern.

DESIGN

Clinicopathologic and selected immunohistochemical analysis of 4 cases of CCRCC mimicking hemangioma.

RESULTS

Cases were seen in 1 woman and 3 men (average age, 48.8 years; range, 40-66 years). Grossly, tumors were red-brown (3 of 4) with scant bright-yellow foci in 1. The average tumor size was 4 cm (range, 2.5-5.5 cm). Microscopically, all were composed of varying proportions of a rich, arborizing, sinusoid-like vasculature with focal hobnail appearance of endothelial cells. Entrapment of renal tubules between blood vessels was seen at the periphery of the tumors. This morphology was reminiscent of anastomosing hemangioma. Isolated tumor cells resembling lymphocytes with clear halos were sparsely interspersed between vessels. Cytokeratin immunostain confirmed the diagnosis of CCRCC.

CONCLUSION

Extensive sampling and immunohistochemical workup of what is deemed to be a benign vascular neoplasm of the kidney is needed to rule out the presence of individual carcinoma cells or small viable carcinoma cell clusters.

Spontaneous regression of biopsy proven primary renal cell carcinoma: A case study

Spontaneous regression of renal cell carcinoma (RCC) is a well-recognized and interesting phenomenon that is poorly understood and rarely documented. There are very few reported cases of spontaneously regressed primary RCC. We present a 63-year-old male with a biopsy-proven RCC that regressed with complete resolution of symptoms.

Spontaneous regression of metastatic renal cell carcinoma: case report

Spontaneous regression of metastatic renal cell carcinoma is rarely observed. A case of suspected spontaneous regression of pulmonary metastases following nephrectomy for histologically proven renal cell carcinoma without systemic treatment is presented along with a brief review of the literature.

Prognostic relevance of extensive necrosis in renal cell carcinoma

AIMS

Evidence suggests that the presence of tumour necrosis is an adverse prognostic factor in renal cell carcinoma (RCC). However, it has also been shown that tumour regression, a microscopic feature associated with necrosis, may be a favourable short term prognostic factor in RCC.

METHODS

Pathology reports of 253 RCCs from 1992 to 2001 were reviewed, and identified 37 tumours with substantial macroscopic or microscopic necrosis. Microscopic pathology, TNM 1997 tumour stage, and clinical follow up were reviewed and correlated with pathological findings. Three cases were rejected because two were diagnosed at necropsy, and a third was the result of renal arterial embolisation.

RESULTS

Twenty of the 34 cases showed <50% necrosis, 10 showed 50-94% tumour necrosis, and four showed >95% tumour necrosis. Follow up data were unavailable in three cases. Nine of the remaining 31 tumours progressed; six were group 3 tumours showing <50% necrosis, three were group 2 tumours showing 50-94% necrosis, and none was a group 1 tumour showing >95% necrosis.

CONCLUSIONS

Extensive necrosis (>95% necrosis) is rare in RCC, accounting for only 1.6% of those diagnosed during eight years in this unselected hospital series. The microscopic pattern of necrosis was typical, requiring extensive tumour sampling for definitive tumour diagnosis. Although there were only four patients with extensive necrosis, none developed recurrent or metastatic carcinoma, or died from RCC. Although extensive (>95%) necrosis may imply better short term prognosis after adjusting for tumour pathological TNM stage, it is probably not a prognostic variable in RCC.

Autonomous histopathological regression of primary tumours associated with specific immune responses to cancer antigens

Spontaneous histopathological regression of cancer has been reported. The involvement of the immune system in such regression has been advocated, leading to the theory of immunological surveillance against cancer. A prediction of this theory is that common tumour antigens can be recognized upon repeated exposure by cell-mediated immunity, which leads to tumour regression and the subsequent appearance of tumour antigen-loss variants. However, no direct evidence has been provided in non-viral-induced experimental animal models of primary malignancy or in human primary cancer. This study examined two groups of melanoma patients where histopathological regression of the primary tumour was observed. Many of the 23 patients with multiple (> or =3) primary melanomas showed significant regression of their last melanoma (median 33%, mean 40) compared with matched melanomas from patients with a single primary melanoma (median 0%, mean 12) (p=0.0080), or compared with their first primary melanoma (p=0.0013). Regression was consistent with an 'immunization effect' seen in murine tumour transplantation studies, where inoculation with > or =3 asynchronous tumours induces transplantation rejection on subsequent challenge. A significant decrease in the expression of the melanoma common tumour antigen MART-1 in the last primary tumour from multiple melanoma patients (median 8%, mean 24) versus matched single melanoma patients (median 79%, mean 68) (p=0.0041) and in the last versus first tumour in multiple primary patients was found (p=0.0083). Metastases from 17 patients whose primary skin melanomas had completely regressed (occult primary melanoma) also showed significant MART-1 loss (median 0%, mean 11) compared with matched metastases from patients with non-regressing primary melanoma (median 51%, mean 50) (p=0.0013). MART-1 antigen-loss variants observed in the multiple primary and occult primary patients correlated with the presence of peripheral blood MART-1-specific cytotoxic T lymphocytes (CTLs) (p=0.03). No similar effects were observed with two other melanoma antigens, gp100 and CD63. Thus, in two groups of human melanoma patients, evidence is provided for histopathological tumour regression associated with cancer immune surveillance.

Simultaneous duodenal and colon masses as late presentation of metastatic renal cell carcinoma

We report a case of pathologically proven simultaneous duodenal and colonic metastases about four years after nephrectomy for mixed clear and granular cell type renal cell carcinoma (RCC). A 76-year-old female patient who had undergone a left radical nephrectomy 4 years previously for RCC presented with a 1-month history of dyspepsia and pain in the right upper abdomen. An abdominopelvic CT scan showed circumferential wall thickening with high enhancement at the second portion of the duodenum and additional enhancement of an irregular protruding mass into the lumen of the ascending colon. A gastroscopy showed a large and ulcerative protruding mass nearly obstructing the second portion of the duodenum. A colonoscopy revealed a polypoid, nodular and purplish mass in the ascending colon. Microscopy of the biopsy specimen showed the features identical to those of the RCC which was resected 4 years earlier in this patient. We believe this to be the first case illustrating a metastatic renal cell carcinoma as simultaneous duodenal and colon masses.

Silencing of the caspase-1 gene occurs in murine and human renal cancer cells and causes solid tumor growth in vivo

Renal cell cancer is a unique solid tumor that occasionally shows spontaneous regression even at an advanced stage, of which the underlying mechanism is not well understood. To investigate a potential role of the pro-apoptotic molecule caspase-1 in the growth regulation of renal cell cancer, we created transfectants expressing exogenous caspase-1 from a murine renal cancer cell line, Renca. Overexpression of caspase-1 did not affect the growth of Renca cells in vitro at the exponential phase but induced apoptotic cell death at 50% to 75% confluence, whereas control cells underwent apoptosis only after reaching 100% confluence. When implanted into the flank of a syngeneic BALB/c mouse, caspase-1-overexpressing Renca cells did not effectively establish growth as a solid tumor, forming a measurable tumor in only 7 of 11 (64%) animals, whereas control cells formed a tumor in 6 of 6 (100%) animals. The growth of tumors from caspase-1-overexpressing cells slowed down markedly after the tumors reached 5 to 10 mm in diameter, and histological examination of such tumors revealed numerous apoptotic cells positively stained by TUNEL assay. Interestingly, endogenous caspase-1 was not detected in the tumors from control cells, which re-expressed caspase-1 when they were re-cultured and exposed to a demethylation reagent, 5-aza-2'-deoxycytidine. Furthermore, treatment of a human renal cancer cell line, ACHN, with 5-aza-2'-deoxycytidine also caused recovery of caspase-1 expression, which was not detected before treatment. These data suggest that silencing of caspase-1 through DNA methylation may be involved in the oncogenesis of some renal cell cancers growing as a solid tumor.

Extensively necrotic cystic renal cell carcinoma: a clinicopathologic study with comparison to other cystic and necrotic renal cancers

Renal cell carcinomas often show varying degrees of necrosis and cystic change. The prognostic importance of necrosis so extensive that only a few tumor cells can be identified is not clear. We gathered clinicopathologic and follow-up data on a group of eight such cases ("type I"). These patients were compared with two other groups of renal cell carcinomas: those with extensive necrosis (>50%), yet with readily identifiable tumor ("type II"), and cancers with extensive cystic change not resulting from necrosis, usually multiloculated ("type III"). The groups showed similar demographic characteristics, and within each group there was great variation in tumor size. Conventional (clear cell) histology was more common than papillary morphology in all groups. The type II neoplasms tended to be of higher nuclear grade and pathologic stage than the other groups. While one of six type I patients with follow up progressed 131 months after diagnosis, eight of 20 type II patients showed progression. None of the six type III patients with follow up progressed. We conclude that renal cell carcinomas showing extensive necrosis are capable of aggressive behavior, and patients with these lesions cannot be assured of cure following surgery. Pathologists must be aware of this entity and extensively sample any renal lesion showing extensive necrosis. The tumors showing a greater amount of viable neoplastic cells yet at least 50% necrosis had a higher rate of progression than did the type I patients. The lack of progression of any of the type III cases supports the idea that type III multiloculated cystic renal cell carcinomas may carry a distinctly better prognosis than other forms of renal cell carcinoma.