MYELOLIPOMA IN THE KIDNEY TRANSPLANT: A UNIQUE ENTITY TO BE ACKNOWLEDGED.

Editor,

Kidney transplantation is the best treatment option for end stage renal disease and the impact of cancer affecting the transplanted graft is higher when compared to the general population. It significantly affects the patient quality of life, meaning return to dialysis, along with worse life expectancy1. It is therefore envisaged to be able to discern between benign lesion treatable conservatively or with surveillance and those requiring graft nephrectomy2. In particular, misdiagnosis of rare entities such as myelolipoma, could represent a challenge requiring dedicate expertise.

Myelolipoma is often incidentally discovered, with no laboratory alterations. Less than 10 cases have been reported in the native kidney as well as in the surrounding tissue3. There is no association with gender and tends to be more common in the seventh decade of life, with the first case described in 1905 by Gierke in the adrenal4, its preferential site. On imaging, it tends to show as a solid mass with fat density attenuation and no contrast-enhancement.

At our Institution, we have treated the only myelolipoma involving a transplanted kidney. This was in a 48 years old male with persistent high C-reactive protein levels, despite no infection source identifiable. His past medical history included Bardet–Biedl syndrome, blindness and kidney failure secondary to reflux nephropathy, for which he underwent deceased donor kidney transplantation 20 years before that worked for 18 years. The failed transplant was left in situ for the remaining two years, on immunosuppression consisting of cyclosporine and prednisolone. At this time, he experienced repeated hospital admission with raised inflammatory markers and fever. On imaging concerns were raised about liposarcoma around his left sided renal transplant (Figure 1). Decision was made to proceed with graft nephrectomy and excision of the retroperitoneal mass (Figure 2). The operation required also ileofemoral arterial bypass and ileofemoral venous bypass in order to achieve radical oncology. Post-operative course was characterised by deep vein thrombosis, for which he was therapeutically treated with enoxaparin. The patient was discharged on 12 days after surgery, with current follow up of 1 month.

Figure 1

Suspected malignant lesion surrounding the left sided kidney transplant (arrow)

Figure 2

Specimen.

In view of this unicity, the majority of clinicians would be unfamiliar with the features and management of myelolipoma in the kidney graft, and indeed even our first diagnosis was of a malignant lesion leading us to pursue a more aggressive treatment, with major vascular reconstruction. The patient was already on dialysis, but more debate regarding the most effective treatment would rise for working grafts. Retrospectively, more awareness of this rare disease, with attention to its radiological features and consideration of risk factors such as endocrine (Bardet-Biedl syndrome) and hematopoietic disorders (long effects of immunosuppression) might have been considered and possibly modified the intended radical oncology.

In conclusion, treatment options of rare benign diseases such as myelolipoma have to be tailored to patient needs, with a conservative management preferable for small, asymptomatic lesions or working grafts and partial/radical nephrectomy in enlarging masses. Embolization is rarely effective, as often the only vascularity present is small and peripheral.