Diagnostic Imaging Corner

Case Challenge

Timothy J Mick (1) and Michelle A Wessely (2)
(1) Center for Diagnostic Imaging (CDI), and Imaging Consultants, Inc.565 Arlington Avenue
West, St Paul 55117, Minnesota, USA mickici@msn.com
(2) Director of Radiology (Paris/Toulouse), Department of Radiology, Institut Franco-Europeen de Chiropratique (IFEC), 24 Boulevard Paul Vaillant Couturier, 94200 Ivry Sur Seine, France
mwessely@ifec.net

Journal of the Academy of Chiropractic Orthopedists
June 2010, Volume 7, Issue 2

This article is available from: http://www.dcorthoacademy.com © 2010 Wessely et at. and the Academy of Chiropractic Orthopedists This is an Open Access article which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Case History

A 62 year old male patient presented to the chiropractor with low back pain that had begun 3 months previously, and has been gradually increasing with time since then. The low back pain was associated with left leg pain extending below the knee. Radiographs were performed and sent to a chiropractic radiologist for interpretation (Figure 1) who following the interpretation recommended further imaging (Figures 2a and b). Of note was that the patient had had a right nephrectomy 2 years previously for renal cancer.

Figure 1.

Figures 2a and 2b.

What are the imaging findings? The upright AP lumbopelvic radiograph (Figure 1) demonstrates a large, aggressive appearing osteolytic process in the left ilium measuring
approximately 9.5 cm in cephalad caudad dimension and at least 11 cm in transverse
dimension, with ill-defined margins and evidence of cortical destruction, especially superomedially at the iliac crest. The lesion extends to the left sacroiliac joint and extension into the adjacent left sacral ala cannot be excluded. With the history of renal cancer, this strongly suggests a large osteolytic metastatic lesion to the left ilium, with possible metastasis to L4 and L5, as well. A portion of the left renal shadow is visualized, with no obvious right renal shadow and metallic surgical staples on the right, consistent with right nephrectomy. No other definite osteolytic or osteoblastic lesions are noted. There is also advanced degenerative disc disease at L5-S1, moderate at L4-5 and mild in the remainder of the lumbar spine. Density changes at L4-5 and L5-S1 may be related to variations in confluent densities and some degenerative reactive sclerosis, but osseous pathology cannot be excluded. No other osseous or joint abnormality is appreciated. Bone density appears to be generally adequate. Soft tissues are otherwise unremarkable.

On the magnetic resonance (MR) imaging of the lumbar spine axial T2- (Figure 2a) and left parasagittal T2-weighted images (Figure 2b), a large aggressive mass with extensive destruction of the left ilium involving the iliac fossa and crest extending to the lateral margin is noted. There are regions of cystic change or necrosis within this heterogenous mass, which are not completely visualized on this exam, but measures as much as 13.0 cm in cephalocaudad dimension, approximately 10.0 cm in coronal plane and at least 9.0 cm in the AP dimension. The left iliac mass extends to but does not definitely cross the left sacroiliac joint. Questionable marrow signal change is noted in the left sacral ala without obvious cortical destruction.

What is your clinical/imaging diagnosis?

The radiographic findings are most consistent with a large osteolytic metastatic lesion in the left ilium and questionable findings at L4 and L5, where degenerative change and/or confluent densities may account for the density variations. The differential diagnosis for the large osteolytic lesion in the ilium includes plasmacytoma or other aggressive processes, but this should be assumed to represent metastatic disease, unless proven otherwise. The MR imaging findings of a large heterogenous cystic and/or partially necrotic mass with extensive cortical and medullary destruction involving the left ilium, elevating the left iliacus muscle and questionable marrow signal change in the left sacral ala as well with the history of renal cancer are consistent with a large expansile metastatic lesion. Differential diagnosis for the iliac mass includes primary sarcoma or plasmocytoma.

What would your clinical management entail?

Follow up of this patient should include immediate oncologic referral, with additional imaging workup to include MRI of the pelvis with and without IV gadolinium contrast and contrast enhanced images of the lumbar spine, along with CT of the bony pelvis. Further imaging workup based upon pending oncologic/clinical findings could also include, but would not be limited to, radionuclide imaging, CT of the chest and imaging of the head to assess for metastasis to these regions. The findings would represent a contraindication to manipulation of the affected regions and since metastatic disease could be radiographically occult in other regions, the findings are considered to represent an absolute contraindication to manipulation at this time.

Final diagnosis:

A CT guided biopsy revealed metastatic renal cancer.

Discussion:

Renal cell carcinomas account for up to 3% of all malignancies affecting the adult population. Renal cell carcinoma is also the most common renal neoplasm, accounting for about 85% of all renal malignancies, of which the clear cell type is the most common (1). Of these, 50% are detected fortuitously (1-3). At the time of presentation, 25 to 30% of patients have metastatic deposits. In the patient presented, it is not sure if this was the case since the imaging presented was performed 2 years post-nephrectomy for renal cell carcinoma. In those patients who receive nephrectomy such as the current patient, up to 50% will develop recurrent or metastatic disease, of which 85% occur within the first 3 years post resection (1). Histologically, they are believed to originate from the epithelium of the proximal convoluted tubules.

The patient tends to be male as in the current patient and in a ratio of 2 to 1 female affected. The patient also has a median age of 80 years old at the time of diagnosis, putting the current patient in a younger age bracket. The patient may present with bone pain, back pain as with this current patient, flank pain or hematuria as some of the classic symptoms and signs. The patient may have a history of smoking, usually heavy smoking. Interestingly, those patients who have worked in metal-related industries with contact with perchloroethylene and tetrachlorocarbonate have an elevated risk of developing renal cell carcinoma (2). In rare cases, the patient suffers from a co-morbidity increasing the risk such as Von Hippel-Lindau disease (2).

Imaging evidence suggestive of malignancy includes the size of the lesion, the presence of calcification and their distribution within the lesion, the presence of septations and thickness of a cyst wall, extension beyond Gerota’s fascia, heterogeneity of the lesion and the appearance of the enhancement post contrast administration. With respect to the size, lesions found to be 7 cms or larger had a higher likelihood of being malignant as were those found to be 3cms or smaller (3, 4).

Many renal masses that eventually are proven to be renal cell carcinomas are originally suggested on imaging studies performed for other reasons. In addition, due to the number of abdominal examinations being performed, especially CT studies, not only has the number of cases of renal carcinoma increased but also, related to earlier detection, so the stage of renal carcinoma has reduced. Renal cell carcinomas may be staged one of two ways using the previous Robson staging system or the updated TMN, both usually being performed with computed tomography (CT). The Robson system determines if the tumor is still confined to the kidney, whether there is extension beyond or limitation by Gerota’s fascia and whether there are distant metastatic lesions. The staging systems are used predominantly for surgical decision making whereby if the inferior vena cava is involved, the surgical approach is altered (4).

Metastatic disease arising from renal cell carcinoma tends to occur to the lung in over half of patients affected, bone in 30 to 40% of patients (such as with the current patient), liver, adrenal gland, contralateral kidney, retroperitoneum and brain (3, 4). In the case of bone metastases as with this current patient, lesions appear as large expansile lytic lesions on radiography, most commonly affecting the axial skeleton. With CT and the addition of contrast, this bone destruction is again seen in addition to which there is also a soft tissue mass which may or may not enhance. Radionuclide studies demonstrate variable uptake and this imaging technique is not currently advocated for the routine evaluation in asymptomatic patients suffering with renal cell carcinoma. MR imaging is often performed as a whole body study although not in this current patient where the symptomatic zone was imaged at the request of the chiropractor and chiropractic radiologist. On MR imaging the fluid sensitive sequences demonstrate hyperintense lesions such as in the current patient, and on the T1 weighted sequences although not available in this current patient for review, focal or diffuse areas of hypointensity are demonstrated (4). In addition, further evidence of metastatic disease affecting the vertebrae includes extension of altered signal intensity in to the pedicular region and extension in to the surrounding soft tissue structures. Although limited availability to positron emission tomography (PET) is available it has been shown to be sensitive and specific in the diagnosis of metatastic disease from renal cell carcinoma.

Treatment has previously consisted of immunotherapy using interferon or interleukin-2 though with low response rates of 10 to 20%. Newer agents have provided mild positive responses or stabilization, for example with tyrosine kinase inhibitors. In addition, as previously alluded to, surgical excision may be proposed especially prior to the immunotherapy. If metastases have already occurred, in the case of a solitary deposit, surgery may provide a survival benefit (5).

Despite the recent advances in therapies to treat renal cell carcinoma, both medical and surgical, the 5 year survival rate is still less than 5%.

Conclusions:

Renal cell carcinoma is a common renal neoplasm affecting the adult population. The initial detection is often fortuitous. Clinical symptoms and signs may be lacking or attributable to other causes including biomechanical ones. Treatment options exist depending on the staging of the tumor. However the prognosis still remains somewhat elusive.

Clinical Pearls:

Renal cell carcinoma occurs in older male patients, who may have a history of smoking and may have worked in the metal industry. Renal cell carcinoma, when metastatic disease is present tends to affect the bones, second in frequency to the lungs. In the bones, it is the axial skeleton that is predisposed, presenting as osteolytic lesions, which may extend in to the pedicles and which on cross sectional imaging may demonstrate extraosseous extension.

Acknowledgements:

The author would like to extend their thanks to the chiropractor.

References:

1) Metastatic renal cell carcinoma Lin SP, Bierhals AJ and Lewis JS Radiographics 2007; 27, 1801- 1807.
2) Occupation, smoking and demographic factors, and renal cell carcinoma in Germany. Schlehofer B, Heuer C, Blettner M, Niehoff D and Wahrendorf J International Journal of Epidemiology, 1995;24,1; 51-57.
3) Imaging in metastatic renal cell carcinoma Griffin N, Gore ME and Sohaib SA AJR. 2007; 189: 360-370.
4) MRI of the kidney—state of the art J. J. Nikken and G. P. Krestin Eur Radiol. 2007; 17(11): 2780– 2793.
5) Renal cell carcinoma: diagnosis and treatment, 1994-2003 Hutson TE Proc (Bayl Univ Med Cent), 2005; 18(4), 337-340.

Further reading:

Taylor J, Hughes T and Resnick D (2010) Skeletal Imaging: Atlas of the Spine and Extremities 2nd edition, Elsevier, USA.

Useful website:

http://radiology.rsna.org/content/247/2/331.full.pdf +html