A 21 years old male presented with a post traumatic comminuted fracture in the proximal one third of right femur. In preparation for surgery his routine investigations were carried out. Chest x-ray revealed no cardiac, pulmonary or mediastinal abnormality. There was no joint space abnormality or foreign body detected in knee radiograph. The complete blood count and differential count were abnormal. The patient was anemic with RBC count 3.32mil/ul (4.7-6.1), hemoglobin 8.6 g/dl (13.0-18.0), hematocrit 26.0% (42.0-52.0) MCV 78.2 fL (80-94), MCH 25.9 pg (27-32) and MCHC 33.1 g/dl (32-36). Sickle cell screening was done and it was negative. His renal functions were unremarkable. Liver function tests were normal except for elevated SGOT 47u/l (15-37) and low levels of serum total proteins 5.2mg/dl (6.4-8.2) and serum albumin 2.4mg/dl (3.4-5.0). Random blood sugar was critically low, 47 mg/dl (<=140). CT scan abdomen and pelvis was advised. It showed an exophytic, complex solid and cystic mass lesion (7x6.5x4.9 cm, cranio-caudal, right-left and antero-posterior dimensions) with thickened walls and septae, replacing the upper pole of left kidney (Bosniak classification type IV). The solid components showed calcification. The lesion appeared to extend into the peri-nephric fat abutting the Gerota's fascia. There was no evidence of invasion into the adjacent organs. A rounded well defined left para aortic lymph node measuring 1.6 x 1.5cm with deeply hypodense center that could represent necrosis was present. A cystic lesion at the level of renal hilum with thick fluid density, possibly representing cystic lymph node was also seen. Another cystic lesion measuring 1.3cm, medial to the adrenal gland was also present. No other lesions were seen in the right kidney, bilateral pelvi-calyceal system, ureters, urinary bladder, pancreas, spleen or liver. Radiological diagnosis of the mass was malignancy versus an infectious process such as tuberculosis. Considering the patient's imaging findings and age, a pathological correlation was advised. The patient underwent left partial nephrectomy.
Gross examination: Received in formalin was a partial nephrectomy specimen of the left kidney, weighing 1240 grams, with a grey brown smooth, glistening surface, measuring 14 x 6.5 x 3.7cm. The anterior surface was lobulated. Ureter measuring 6.5 x 0.4 cm was identified at the hilar area along with sutured blood vessels. On opening the kidney, a solid, cystic lesion measuring 7 x 6x 5cm was identified. The cysts were multiple and they ranged from 1-3cm in size. Two tan brown lymph nodes, one hilar and one suprahilar, measuring 2cm and 1.5cm in maximum dimensions, respectively, were also identified and sampled.
Microscopic examination: Examined sections revealed a malignant tumor (Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6, Figure 7) comprising cysts, papillae and large foci of undifferentiated solid tumor showing extensive calcification, focal bone formation and cartilaginous differentiation. The cells lining the papillae and the cysts were eosinophilic, showing areas of stratification with vesicular, pleomorphic nuclei and prominent nucleoli. The solid areas showed diffuse sheets of blue cells with hyperchromatic, pleomorphic nuclei and scanty cytoplasm with foci showing abortive tubular formation. The tumor was seen extending into the peri-nephric fat. Lympho- vascular invasion was not identified. The two lymph-nodes sampled were seen to be completely replaced by the tumor.
Immunocytochemistry: The tumor cells were positive for Cytokeratin(CK) - 7, CK-18, CK-19, High Molecular Weight Cytokeratin (HMW-CK), AE1/AE3 and Vimentin, Alpha Methyl Acyl Coenzyme A Racemase (AMACR), RCC marker, PAX-8 and Vimentin. These were negative for CD10, CD45, CD117, and Wilms Tumor (WT)-1. CK5/6, Melan A, HMB-45 and S-100.
Cytogenetic studies: There was no gain of chromosome 7 and/or 17 and also no loss of chromosome Y in both solid and papillary areas.