Schlomer B et al. (2006) How does the radiographic size of a renal mass compare with the pathologic size? Urology 68: 292–295

The size of renal tumors on CT or X-ray images is often used to decide whether a patient is suitable to undergo nephron-sparing surgery (NSS). Previous studies that compared the apparent size of renal tumors on CT or X-ray images with the actual size of pathologic specimens have yielded conflicting results. Schlomer and colleagues, therefore, conducted a retrospective study in 126 patients with a renal lesion suspicious for renal cell carcinoma, in whom CT was performed ≤60 days before surgery. Clinical size was defined as the largest tumor measurement on CT; pathologic size was the largest measurement seen at pathology.

For all 133 tumors detected, mean clinical size did not differ significantly from mean pathologic size. In terms of tumor stage, clinical size was markedly greater than pathologic size only for tumors >4 cm and graded T1a or T3a. Mean clinical size was larger than pathologic size for tumors >7 cm; this difference was substantial for tumors 1–2, 2–3, 3–4, and 4–5 cm in size.

The greatest difference between mean clinical and mean pathologic size (0.87 cm) was seen for tumors 4–5 cm in size, which the authors suggest might lead to some patients with tumors of clinical size <4 cm—who are usually suitable for NSS—not receiving this treatment; additionally some patients with tumors of clinical size >4 cm might be suitable for NSS after consultation. Prospective studies that examine other factors associated with the difference between clinical and pathologic size (including tumor location and presence of hematomas) are required.