Renal Extra Skeletal Mesenchymal Chondrosarcoma: A Case Report.

Primary mesenchymal chondrosarcoma of the Kidney is an extremely rare entity and very few cases have been reported in literature. We report a 22-year-old male with a right renal mass; after radical nephrectomy, pathologic examination revealed primary extra skeletal mesenchymal chondrosarcoma.

Introduction

Mesenchymal chondrosarcoma (MC) is a quite rare disease. Bone is the most common organ affected by MC, but one-third of mesenchymal chondrosarcomas originate in the soft tissue and other organs. Most cases of extra skeletal mesenchymal chondrosarcomas are seen in the head and neck region followed by the extra mities and trunk.

Herein, we report a case of MC of the Kidney in a young male. To the best of our knowledge, only nine cases of MC of the kidney have been described in English literature so far.

Case presentation

A 22-year-old male presented with a 2-month history of vague right flank pain that exacerbated since 2 weeks prior to admission. The patient had a negative history of gross hematuria, trauma and fever. His past medical history was unremarkable. Physical examination revealed mild right costovertebral angle tenderness without abdominal organomegaly. The laboratory findings were as follows:

Liver function test and chest X-ray were normal. Urinalysis showed microhematuria.

Abdominopelvic Ultrasonography showed a large cystic structure (90 mm in diameter) located in the posterolateral portion of the mid pole of the right kidney with large areas of calcification and significant wall thickening. Abdominopelvic CT scan demonstrated a large heterogeneous mass with some areas of course calcification in the mid part of the right kidney that enhanced after administration of contrast material (Fig. 1).

Figure 1

Abdominal CT scan showed: (A) a heterogeneous mass in the mid pole right kidney with some areas of calcification. (B) The mass enhanced after contrast material administration.

Thus, with priminaly diagnosis of renal malignancy the patient underwent right radical nephrectomy through a mild line abdominal incision. Histological examination indicated a hypercellular tumor with round to spindle shaped hyperchronic cells with indistinct cytoplasmic borders and inconspicuous nucleoli (Fig. 2A). There were areas of abnormal tortuous blood vessels (Hemangiopericystic pattern like) (Fig. 2B). Islands of mature and immature cartilage with ossification foci were also seen (Fig. 2C). There were foci of necrosis (10–20). There was no sign of invasion to the capsule, lymphovascular, and perineural. The ureter and vascular margin were free of tumor.

Figure 2

(A) Sections from renal mass (right side: renal parenchyma, vertical arrow) show hypercellular tumor with small and spindle hyperchromatic cells (left side, horizontal arrow); H&E ×100. (B) Sections from renal mass show hypercellular tumor with many small stag-horn blood vessel; H&E ×250. (C) Sections from the renal tumor show cartilage formation (arrow); H&E ×250.

Immunohistochemical (IHC) staining showed:

BCL2: Positive, CD10: Negative, CD34: Negative, C.Kit: Negative, Cytokeratin (AE1, AE3): Negative, Desmin (D33): Negative, Ki67 (MIb-1) = 30%

LDA (2Bt1 + PD7/26): negative, MICS (CD99) (12E7): Positive, MODY (5-8A): Negative, S100: Negative, SMA (1AY): Negative, Vimentin (Vim 3 BY): Positive, WTT (6F-H2): Negative

IHC findings on paraffin-embedded formalin-fixed tissue were in favor of MC.

Discussion

MC is a high grade malignancy of the bone and soft tissue. It represents only 2% of all chondrosarcomas. MC of the kidney is a very rare entity. In literature review, only nine cases of it have been reported so far. The clinical manifestations of renal MC (RMC) are non-specific, among which pain, microscopic or gross hematuria, and mass are the most common features. Imaging study of choice for evaluating of any renal mass is CT scan. In CT scan, RMC is usually seen as soft tissue masses with dense and granular calcification; however, they may also present as heterogeneous and hypodense masses without calcification. The definitive diagnosis is based on the histopathologic findings. MC has a biphasic pattern composed of islets of well-differentiated cartilage surrounded by undifferentiated spindle mesenchymal cells. In addition, Immunohistochemical markers aid in diagnosis of MC.

Because of the rarity of RMC and lack of appropriate clinical studies, there are no optimal treatment protocols for management of RMC. Although the role of systemic chemotherapy or radiotherapy has not been evaluated in RMC, it seems that complete surgical resection with clear margins and adjuvant chemotherapy increase the patient's survival rate.3, 5 Recommended chemotherapy regimen for MC is a combination of vincristine, doxorubicin and cyclophosphamide alternating with ifosfamide and etoposide. Increased expression of the platelet-derived growth factor receptor α (PDGFR-α) was reported in malignant mesenchymal cells, so target agents such as dasatinib, imatinib, sorafenib and sunitinib that inhabit PDGFR-α function may play a role in treatment of MC.

The prognosis of MC of the bone and soft tissue is poor. Because of the rarity of RMC, the prognosis for this entity is unknown. So regular follow-up is mandatory for early detection of local recurrence and distant metastases.

Conclusion

Renal MC is very rare. Although it is difficult to say with certainly, complete surgical resection and adjuvant chemotherapy may improve the outcome of the patient. Due to aggressive behavior and tendency toward metastasis, regular follow-up is recommended.

Conflicts of interest

The authors declare that they have no conflict of interest.