Renomedullary interstitial cell tumor (formerly fibroma of renal medulla)

Renomedullary Interstitial Cell Tumor in the Background of a Renal Oncocytoma: A Case Report

Renomedullary interstitial cell tumors (RMICTs) are rare benign renal tumors that arise from the renal medulla. They are rarely symptomatic and are mostly discovered incidentally. Radiologically, their co-presence ipsilaterally in the background of a larger mass introduces a miscellaneous presentation that raises the suspicion of metastatic disease. A characteristic presentation does not exist. Therefore, an individualized, patient-centered approach should be tailored depending on the nature of the presentation. We report the clinical, radiological, and histopathological presentation of a 46-year-old woman presenting with an RMICT in the background of a renal oncocytoma.

A case of renomedullary interstitial cell tumor: Radiologic-pathologic correlation

Renomedullary interstitial cell tumor (RMICT), referred to as a medullary fibroma, is almost always asymptomatic and incidentally identified either at autopsy or upon resection of the kidney for other reasons. Although a few cases of RMICTs that are large in size and clinically symptomatic have been reported, there are few reports of RMICTs contrasting imaging findings with pathological findings. In this report, we describe a relatively large RMICT case of 3 cm in size, focusing on the radiologic-pathologic correlation.

Potential clinical implications of an incidental renomedullary interstitial cell tumor in renal allograft biopsy

Renomedullary interstitial cell tumors (RMICTs) are often incidentally detected lesions at autopsy or resection of the kidney for other reasons. The RMICTs have not been reported in renal allograft biopsy. Overall, given the clinical implications of the differential diagnosis considered, such as morphologically similar neoplasms, interstitial fibrosis and tubular atrophy (IFTA), amyloidosis, and oxalosis, it is prudent to exclude these by an appropriate workup. Once excluded, the patients can be reassured. However, regular follow-up is recommended due to the propensity of RMICT to increase in size with age.

Renomedullary Interstitial Cell Tumor Mimicking Renal Cell Carcinoma: A Case Report

Renomedullary interstitial cell tumors are often incidentally identified either upon autopsy or kidney resection for other reasons. However, rare renomedullary interstitial cell tumor cases resulting in a clinical symptomatic mass have been reported. We present a case of renomedullary interstitial cell tumor that was manifested as an incidentally detected renal mass and mimicked renal cell carcinoma on the imaging features.

Adolescent Renomedullary Interstitial Cell Tumor: A Case Report

A 14-year-old boy presented with painless gross hematuria after a blunt trauma to his right lumbar region. Abdominal ultrasonography and abdominal computerized tomography revealed that the right kidney was hydronephrotic; contrast material delineated a hematoma inside the kidney. The patient underwent a right simple nephrectomy and after histopathological examination was found to have a renomedullary interstitial cell tumor of the right kidney. This tumor is common in patients older than 50 years, whereas our patient was very young. The diagnosis of this small tumor is not possible by conventional radiological techniques and histopathological examination is mandatory for its diagnosis.

Immunohistochemical characteristics of renomedullary interstitial cell tumor: a study of 41 tumors with emphasis on differential diagnosis of mesenchymal neoplasms

Renomedullary interstitial cell tumors (RMICTs) are almost always incidentally identified either at autopsy or upon resection of the kidney for other reasons. However, rare cases that are large, resulting in a clinical mass, have been reported. The immunohistochemical phenotype of usual, incidental RMICT using modern soft tissue tumor markers is largely unknown, however, providing little information to aid in classification of larger or atypical tumors. We retrieved 41 RMICTs from 36 patients and studied pathologic characteristics including morphology, immunohistochemistry (S100, keratin AE1/AE3, smooth muscle actin, desmin, estrogen and progesterone receptors, calponin, CD34, CD35), and histochemical staining. Data collected included age, sex, tumor size, laterality, and indication for kidney examination. RMICTs (n = 41) were identified in 23 men and 13 women, with a mean age of 57 years (range, 24-83 years); tumor sizes ranged from less than 1 to 13 mm (median, 4 mm). Kidneys were resected for 32 tumors, 1 chronic pyelonephritis, 1 trauma, and 2 autopsies. All (41; 100%) had entrapped renal tubules, 5 (12%) of which included cystic or dilated tubules. Most (35; 85%) had collagenous fibers, all of which were negative for Congo red. RMICT demonstrates a largely negative immunohistochemical phenotype with weak-to-moderate labeling for smooth muscle actin and calponin that is substantially less than myofibroblastic lesions. Positive staining for estrogen and progesterone receptors is common (61%), which could overlap with mixed epithelial and stromal tumor and other entities; however, staining is typically weak. CD34 is usually negative, with occasional weak labeling, in contrast to solitary fibrous tumor.

Clinicopathologic features of renomedullary interstitial cell tumor presenting as the main solid renal mass

OBJECTIVE

To review the clinical, pathologic, and radiographic features of renomedullary interstitial cell tumor (RMICT). This is a rare benign renal tumor formerly known as medullary fibroma and is indistinguishable from other renal cortical tumors by imaging.

METHODS

After institutional review board approval, we reviewed data on patients from the Memorial Sloan-Kettering Cancer Center kidney tumor database from 1989 to 2012 (4898 patients) with a pathologic diagnosis of RMICT or medullary fibroma as the main resected tumor. Data collected included procedure, age, gender, presentation, preoperative tumor characteristics (size, location, nearness to collecting system, and RENAL nephrometry score), and final pathologic size.

RESULTS

Ten patients (0.2%) with RMICT were identified. All patients had undergone partial nephrectomy for 10 tumors (9 right). Clinical presentation was incidental to abdominal imaging performed for another clinical reason in 6 patients, as part of a hematuria evaluation in 2 patients, and as part of nephrolithiasis follow-up imaging in 2 patients. The mean patient age was 52 years (range, 39-73), and 8 patients were female. The mean preoperative and final pathologic tumor size was 1.65 cm (range, 1.0-2.5) and 0.96 cm (range, 0.3-1.7), respectively. The location of the tumors was medullary (0-9 mm from the collecting system) in 8 patients and cortical (2.5 cm mostly exophytic and 1.5 cm mostly endophytic tumor) in 2 patients.

CONCLUSION

Our data demonstrate a female predominance, a mean tumor size of <2 cm, and medullary location consistent with its pathologic origin. To our knowledge, this is the largest single-institution series of RMICT.

Incidental solid renal mass in a cadaveric donor kidney

The number of patients living with end-stage renal disease (ESRD) is increasing in our country and demand for renal grafts is ever increasing. Cadaver renal transplantation is being established as a viable supplement to live transplantation. We present a case where a mass lesion was encountered in the donor kidney from a cadaver. Enucleation of the lesion was done and we proceeded with the grafting. Histopathological examination showed a ‘Renomedullary interstitial cell tumour’, a rare benign lesion. Post transplant, the renal function recovered well and the patient is asymptomatic. Such incidental renal masses present an ethical dilemma to the operating surgeon.

Histopathological, immunohistochemical and ultrastructural studies of a renal mesenchymal tumor in a young beagle dog

A 15-month-old male beagle dog used in a toxicity study had a primary renal mesenchymal tumor. Macroscopically, the tumor was a gray-white mass which was found in the right kidney, and extended from the capsule to a position slightly compressing the medulla. Microscopically, most of the tumor cells showed a myxoid pattern, in which the matrix was positive for alcian blue staining. In the other parts of the tumor, a fascicular and wavy pattern was observed, and the matrix was full of collagen fibrils. Immunohistochemically, tumor cells were positive for vimentin and fibronectin, and negative for cytokeratin, desmin, α-smooth muscle actin, Von Willebrand factor, cyclooxigenase-2 and myelin basic protein. As a result, we diagnosed this case to be a renal mesenchymal tumor. Based on the microscopic findings, interstitial characteristics and immunohistochemical features, the present case was classified as a congenital mesoblastic tumor.

Persistent Hypotension Associated with Hypermedullipinemia: A New Syndrome

A new syndrome is described in a patient with advanced renal insufficiency. This consists of severe and persistent hypotension causing weakness but associated with a clear mental status. Also present is evidence for decreased vascular reactivity. The hypotension was not orthostatic. The hypotension was associated with a circulating vasodepressor substance having the characteristics of medullipin 1. The medullipin appears to have been derived from the remaining right kidney. Hypotension existed despite the presence of major prohypertensive mechanisms, including an endstage kidney, hyperreninemia and hyperaldosteronemia. It is likely that hypotension due to hypermedullipinemia is an entity occurring in the human being.

Benign renal neoplasms in adults: cross-sectional imaging findings

OBJECTIVE

A broad spectrum of benign renal neoplasms in adults shows characteristic ontogeny, histology, and tumor biology. Benign renal tumors are classified into renal cell tumors, metanephric tumors, mesenchymal tumors, and mixed epithelial and mesenchymal tumors. Select benign tumors show characteristic anatomic distribution and imaging features. However, because of overlapping of findings between benign and malignant renal tumors, histologic evaluation may be required to establish a definitive diagnosis. Accurate preoperative characterization facilitates optimal patient management.

CONCLUSION

We attempt to provide a comprehensive, contemporary review of benign renal neoplasms that occur in adults, focusing on cross-sectional imaging characteristics.

Calcium oxalate precipitates in a renomedullary interstitial cell tumor

We report a case of calcium oxalate deposition in a renomedullary interstitial cell tumor (RICT) in a patient dying of full-blown AIDS. The precipitates showed birefringence using a partially polaris ed light and were stained black in Yasue's silver nitrate-rubeanic acid method. The combination of calcium oxalosis and RICT has not been reported before and might possibly be due to systemic biochemical alterations of the glycosaminoglycans as a result of profound metabolic disturbances in AIDS patients.

The role of ultrastructural pathology in the diagnosis of epithelial and unusual renal tumors

The electron microscopic and immunohistochemical features of epithelial and unusual renal tumors are reviewed. Ultrastructural and immunohistochemical features of diagnostic value are highlighted. An attempt is made to address histogenesis/differentiation issues that would help in understanding morphologic findings, with an emphasis placed on the role that ultrastructural evaluation has played in demonstrating these.

Giant renomedullary interstitial cell tumor

We report a case of a tumor of the renal medulla. Tumor cells were characteristic of renomedullary interstitial cells as demonstrated by light microscopy, immunohistochemistry and electron microscopy. Such masses are usually small (less than 0.5 cm.) and incidental. This neoplasm, however, was 5.0 cm. in diameter. To our knowledge, our case is unique because of tumor size and because it is the first report of an interstitial cell tumor of the kidney that has been clinically observed and surgically excised.

Case of renal medullary fibroma

An unusual case of renal medullary fibroma accompanied by gross hematuria is reported. This is the eleventh reported case of this disease producing clinical symptoms.

Irreversible damage to the medullary interstitium in experimental analgesic nephropathy in F344 rats

Renal papillary necrosis (RPN) and a decreased urinary concentrating ability developed during continuous long-term treatment with aspirin and paracetamol in female Fischer 344 rats. Renal structure and concentrating ability were examined after a recovery period of up to 18 weeks, when no analgesics were given, to investigate whether the analgesic-induced changes were reversible. There was no evidence of repair to the damaged medullary interstitial matrix, or proliferation of remaining undamaged type 1 medullary interstitial cells after the recovery period following analgesic treatment. The recovery of urinary concentrating ability was related to the length of analgesic treatment and the extent of the resulting inner medullary structural damage. During the early stages of analgesic treatment, the changes in urinary concentrating ability were reversible, but after prolonged analgesic treatment, maximum urinary concentrating ability failed to recover. This study shows that prolonged analgesic treatment in Fischer 344 rats causes progressive and irreversible damage to the interstitial matrix and type 1 interstitial cells leading to RPN. The associated urinary concentrating defect is reversible only during the early stages of structural damage to the inner medulla.

Alterations in blood pressure by derangement of the mechanisms that regulate sodium excretion

Understanding the sequence of events responsible for pressure-related natriuresis and their pathophysiologic alterations may be useful in distinguishing various types of essential hypertension of renal origin. The perturbation of a distal step in the sequence is likely to be reflected in a simple physiologic defect. For instance, pathophysiologic alterations in the medullary production of prostaglandin E2 might directly influence natriuresis and diuresis because of its modulatory effect on tubular reabsorption of sodium and water. Perturbation of more proximal steps in the sequence could influence all the distal events as well. For instance, prostaglandin I2 and endothelium-derived relaxing factor may be produced by the preglomerular vasculature in response to alterations in renal perfusion pressure and may modulate the release of renin from the juxtaglomerular cells. Thus, variations in the production of prostaglandin I2 or endothelium-derived relaxing factor may be reflected by various renal vascular, tubular, and systemic homeostatic events related to the renin-angiotensin system.

The small cystic and noncystic noninflammatory renal nodules: a postmortem study

We report the incidence and features of small cystic and noncystic noninflammatory renal lesions found in a series of 500 unselected necropsies performed for forensic reasons in a Portuguese population. A total of 997 kidneys was sectioned serially in 0.2 cm. sections. There were 1,256 lesions (the large majority being less than 1 cm.) found in 380 examined organs belonging to 265 cases. A total of 1,105 cystic lesions was observed in 195 (39 per cent) specimens, 108 medullary fibrous nodules in 89 (17.8 per cent), 29 cortical adenomas in 20 (4 per cent), 5 leiomyomas in 5 (1 per cent), 4 lipomas in 4 (0.8 per cent), 2 fibromyolipomas in 2 (0.4 per cent) and 3 fibromas of the capsule in 3 (0.6 per cent). Cystic lesions showed an increase in number with patient age, which does not occur with medullary fibrous nodules. Cortical adenomas were most frequent at the fifth and sixth decades of life. The risk of malignancy, with the possible exception of some of the cortical adenomas, is believed to be small.

Clear cell sarcoma of the kidney: a clinicopathologic study of 21 patients with long-term follow-up evaluation

The clinical and pathologic features of 21 children with clear cell sarcoma of the kidney are presented. These cases were identified among 517 primary renal tumors collected from four pediatric institutions. Abdominal mass and hematuria were the usual presenting signs. The male to female ratio was 1.3 to 1. Although the mean age at diagnosis was 3 years, the sarcomas were diagnosed earlier in boys (2 years, 7 months) than in girls (3 years, 7 months). Tumor size and weight may have accounted for this difference, since the average tumor weights were 899 g for boys and 635 g for girls. Right kidney locations predominated (14 cases). The most common site for metastasis was the skeleton (12 patients), and the skull was almost invariably involved (10 children). Bone metastases preceded the development of metastases elsewhere in nine patients, in five of whom the involvement was polyostotic. Of the 12 patients with osseous metastases, nine died within five years of diagnosis, and one died eight years and nine months after diagnosis; the remaining two patients were successfully treated with a combination of surgery, radiotherapy, and actinomycin D, vincristine, cyclophosphamide, and Adriamycin. Eight of the nine patients with lung metastases died within five years of diagnosis. Until substantial proof is found that clear cell sarcoma of the kidney is related to nephroblastoma, its identification as a non-Wilms' sarcoma would seem to be appropriate. This tumor is not the only sarcoma of the kidney, but it appears to be the most common renal sarcoma of childhood.

Clear cell sarcoma of the kidney with emphasis on ultrastructural studies

Clear cell sarcoma of the kidney (CCSK) is a malignant childhood tumor distinguished from Wilms' tumor by its gross, microscopic, and ultrastructural morphologic features and its propensity to metastasize to bone. Some clinical features of 75 cases of CCSK registered in the National Wilms' Tumor Studies I-III are presented along with the results of electron microscopic study of 12 tumors. Ultrastructural features of the tumor are compared to those of tumors of pericytes, Schwann's cells, renomedullary interstitial cells, fibroblasts, other renal tumors, and other clear cell tumors. Fine structural properties of primitive cells with variable numbers of organelles do not strongly suggest a histogenetic origin. The effect of formalin fixation on perinuclear cytoplasmic filaments and the tendency of tumor cell extensions to enfold the pale extracellular matrix explain the vacuolated appearance of some tumor cells.

Hypertension due to a renin-secreting tumour localised by segmental renal vein sampling

An 18-year-old female was found to be hypertensive on routine medical examination. Further investigation disclosed persistent hypokalaemia and elevated plasma renin activity in peripheral venous blood. Segmental renal vein sampling with assay of blood samples located the source of excess renin secretion in the lower mid-zone of the left kidney. This localization was not confirmed by either angiography or by palpation of the exposed kidney before nephrectomy but macroscopic examination of the freshly sectioned kidney revealed a small tumour in the region suggested by renal vein sampling. The tumour had the morphologic pattern fo an haemangiopericytoma with abundant ultrastructural specific granules and very high renin activity by tissue assay. Plasma renin activity fell precipitously after nephrectomy and remained very low for the first week. Although the immediate post-operative blood pressure fell to normal, hypertension recurred temporarily and was associated with elevated plasma aldosteron, producing a syndrome similar to primary aldosteronism. All variables returned to normal without specific therapy and hypertension has not subsequently recurred.

Renal prostaglandins and the regulation of blood pressure and sodium and water homeostasis

In addition to its well known prohypertensive role in various states of experimental and human hypertension, the kidney has also been shown to exert an antihypertensive "endocrine" function. According to this hypothesis, certain forms of experimental and human hypertension might not solely be the result of an excess in the activity of such renal pressor systems as the renin-angiotensin system and the sympathetic nervous system, but might also result from an absolute or relative deficiency of intra-renal vasodilator antihypertensive factors which might allow pressor systems to act unopposed to produce peripheral arteriolar vasoconstriction and sustained hypertension. At least four factors have been characterized in the kidney of various animal species and man which might be responsible for such an antihypertensive function. These are (1) the renomedullary prostaglandins (PGs), (2) the renomedullary antihypertensive neutral lipid, (3) antirenin phospholipid and (4) the renal kinins. This review is restricted to an examination of the possibility that the vasodepressor renomedullary prostaglandins (PGA and/or PGE) may, at least in part, mediate the so-called antihypertensive function of the kidney and participate in the regulation of renal blood flow and natriuresis by physiologic antagonism of various renal vasoconstrictor stimuli such as the renal renin-angiotensin and the sympathetic nervous systems.

Renomedullary interstitial cell lesions and hypertension

The notion that renomedullary nodules of the kidney arise as a response to hypertension was tested. Heart weight, ratio of heart weight to body weight, and blood pressure in 160 patients in whom such nodules were found at autopsy were compared with similar measurements in 160 patients without nodules. There were no significant differences between the two groups, and it was concluded that there was no evidence to support the idea that the renomedullary nodule represents a response to hypertension.

Bartter's syndrome with hyperplasia of renomedullary cells: successful treatment with indomethacin

During treatment with indomethacin in a patient with Bartter's syndrome, hypokalemia, high plasma renin concentration, hyperaldosteronism and decreased sensitivity to angiotensin infusion were corrected. A particular finding in the renal biopsy specimen was a marked hyperplasia of renomedullary interstitial cells which had characteristics similar to the cells known to produce renal prostaglandins. The hypothesis is formultated that the primary defect in this syndrome is related to hyperplasia of renomedullary interstitial cells and inappropriate release of renal prostaglandins giving rise to decreased sodium reabsorption, volume depletion and hypersecretion of renin and aldosterone.