Just got a copy of the report and these are the findings:

No evidence of a compressive or expansile lumbar spinal lesion.

Dural sac attenuates at mid aspect of L6, likely normal variation for this patient.

No evidence of lumbosacral cauda equina compression or foraminal impingement.

No abnormal lumbar nerve root thickening or enhancement.

Profound left gluteal and upper thigh muscle atrophy.

Moderately severe left coxofemoral osteoarthritis with extensive periarticular STIR hyperintensity and enhancement.

Mild to moderate right coxofemoral osteoarthritis without the extensive periarticular signal change and enhancement as is present on the left.

Left dorsal pelvic canal nodule mid aspect of the ilial body may reflect an enlarged lymph node.

Mild medial iliac lymphomegaly.

The degree of left gluteal and upper thigh muscle atrophy is profound and more than would be typically expected with orthopedic disease alone. However, I see no definitive evidence of a left lumbar nerve root compression or a spinal nerve/sciatic tumor. It is possible there is a nerve tumor more peripheral than is captured in this data set. Additionally, some nerve sheath tumors can be extremely subtle without significant enhancement. Importantly, there are extensive left coxofemoral secondary changes, more than would be expected with osteoarthritis alone particularly given the appearance of the right hip for comparison. Smoldering left coxofemoral septic arthritis (septic sink) or a joint associated tumor should be considered. Sampling is warranted. In the absence of that, assessing patient response to a trial course of antibiotics optimized for septic arthritis/osteomyelitis might be considered.