International Journal of Urology (2012) 19, 92–93
Letter to the Editor
iju_2904
doi: 10.1111/j.1442-2042.2011.02904.x
92..93
Metastatic clear cell renal cell carcinoma to the adrenal gland without an identifiable primary tumor The development of metastatic disease without evidence of a primary malignancy is rare and might represent spontaneous regression of the primary cancer of unknown origin or delayed development of the primary or ectopic tissue, giving rise to tumor. A 71-year-old man presented with back pain and a 3.8-cm left adrenal mass on computed tomography (CT; Fig. 1a). Serum functional work-up was negative. Subsequent imaging showed enlargement of the lesion. Laparoscopic adrenalectomy 5 months later showed a 4.8-cm mass with negative margins (Fig. 1b). Histology showed a neoplasm composed of clear cells with prominent cell borders diagnostic for clear cell renal cell carcinoma (RCC), surrounded by the adrenal cortex (Fig. 1c). Immunostains, PAX2, PAX8, carbonic anhydrase IX, RCC, CD10, vimentin, AE1/3 and EMA, were positive, and melan-A, inhibin, S100, synaptophysin and PSA were negative. Expert outside consultation concurred. An involuted region in the left kidney was consistently seen on all pre- and postadrenalectomy imaging (Fig. 1d). There was no evidence of a primary RCC, ectopic or supernumerary kidney. The patient has been followed with imaging every 6 months, including CT and positron emission tomography, without evidence of RCC during 3 years of follow up.
(a)
(b)
(c)
(d)
1 µm
92
Spontaneous regression of primary RCC with or without metastatic disease is limited to five cases.1–4 There was no history of chemotherapy or immunotherapy in these cases or the present patient. Choi reported a nephrectomy with minimal viable tumor, described as “clusters of tubular structures of varying sizes,” but carried out no ancillary studies.1 Although the authors stated a diagnosis of RCC (subtype unspecified), the description and photomicrograph are inconsistent with RCC. Edwards identified a patient with a renal mass and lung nodules.2 A nephrectomy specimen documented RCC (subtype unspecified) with marked fibrosis and necrosis, but included no histological description or photomicrograph. Hamid noted two patients with nephrectomy specimens containing minimal viable tumor.3 Histological description and photomicrographs in patient 1 were consistent with clear cell RCC. Patient 2 had a tumor designated as RCC (subtype unspecified), without a histological description or photomicrograph. Kobayashi described a case with a renal mass extending into the inferior vena cava.4 Biopsy showed “malignant cells.” On imaging, the mass size had decreased with tumor thrombus resolution. A nephrectomy was not carried out. There has been one case of metastatic RCC diagnosed without an identifiable primary in which primary tumor was observed 4 months later.
Fig. 1 (a) Computed tomography (CT) of the abdomen and pelvis showing a heterogenous adrenal lesion before adrenalectomy. Arrow points to the adrenal mass. (b) Gross adrenalectomy specimen measuring 8.0 ¥ 4.5 ¥ 3.3 cm and weighing 48.1 g. Scale bar denotes centimeter divisions. (c) Hematoxylin–eosin stained section of the adrenalectomy specimen showing clear cell renal cell carcinoma on the right with compressed nests of non-neoplastic adrenal cortex on the left. Scale bar, 1 mm (magnification: ¥200). (d) CT of the abdomen and pelvis with an involuted portion of the left kidney, identified by an arrow. © 2011 The Japanese Urological Association
Letter to the Editor
Spontaneous regression of primary RCC is poorly defined , encompassing pathological and radiological descriptions. In pathological specimens, all prior cases had areas of viable tumor.1–3 It is unknown if the presence of viable tumor is acceptable to denote a designation of regression or how much viable tumor is permissible. In radiologically-defined regression, a renal mass remained in all serial photographs.2,4 It is unclear what amount of size reduction qualifies as regression. The mechanism of spontaneous regression is unknown, although it is likely to be multifactorial involving immune and non-immune factors. Spontaneous regression in melanoma has been associated with multiple primary tumors and increased T-lymphocytes in the regressed specimens. Thymoma can show spontaneous regression as a result of infarction. Similar phenomena can occur in the kidney. Matthew T Johnson M.S., M.D.,1 Robert R Bahnson M.D.1 and Debra L Zynger M.S., M.D.2 Departments of 1Urology and 2Pathology, The Ohio State University Medical Center, Columbus, Ohio, USA
[email protected]
© 2011 The Japanese Urological Association
Conflict of interest None declared.
References 1 Choi SK, Chang SK, Lee JM, Jung WH, Park CI. Spontaneous regression of primary renal cell carcinoma – a case report. Yonsei Med. J. 1986; 27: 314–17. 2 Edwards MJ, Anderson JA, Angel JR, Harty JI. Spontaneous regression of primary and metastatic renal cell carcinoma. J. Urol. 1996; 155: 1385. 3 Hamid Y, Poller DN. Spontaneous regression of renal cell carcinoma: a pitfall in diagnosis of renal lesions. J. Clin. Pathol. 1998; 51: 334–6. 4 Kobayashi K, Sato T, Sunaoshi K, Takahashi A, Tamakawa M. Spontaneous regression of primary renal cell carcinoma with inferior vena caval tumor thrombus. J. Urol. 2002; 167: 242–3.
93
