Loss of function of the adenomatous polyposis coli (APC)͞Apc tumor suppressor gene occurs early in the etiology of intestinal cancer in mammals. In human colonic tumors, genomic instability is proposed to be associated with tumor initiation by inducing loss of APC function. We have used a mouse model of inherited intestinal cancer (Apc Min ͞؉, Min͞؉) to analyze the earliest stages of tumorigenesis in this organ. We find that tumors from C57BL͞6 Min͞؉ mice have a stable karyotype and stable microsatellites. In contrast to previous claims, we find that homozygosity for the Min allele of Apc in tumors can proceed by homologous somatic recombination. Further, our analysis of early, benign human colorectal adenomas failed to reveal any evidence for generalized chromosomal or microsatellite instability. These results cast doubt on the hypothesis that either of these forms of genomic instability is necessary for the initial development of colorectal adenomas. We contrast our analysis of autochthonous primary tumors to other studies involving xenografts or cultured cells.

We reviewed 119 percutaneous, radiologically guided fine-needle aspirations (FNA) from 114 patients with liver masses to evaluate diagnostic effectiveness and complications of this procedure. Satisfactory material was obtained in 118 cases (99%), of which 78 were diagnosed as positive (66%), three suspicious (2%), five atypical (4%), and 32 (27%) as negative for malignancy. Compared to surgical biopsy (48 cases) and clinical data, the sensitivity and specificity of FNA for malignancy was 95.1% and 100%, respectively, yielding a positive predictive value of 100% and a negative predictive value of 88.8%. Four cytology cases (3.4%) were false-negatives (FN); all were interpretive errors. Four FN surgical biopsies (8.3%) were sampling errors. Minor complications occurred in three cases (2.5%). We conclude that FNA is safe and effective for determining the malignant potential of liver masses and should be the procedure of choice. Our experience suggests that having a pathologist present in the radiology suite provides optimal patient care.

The described histologic characteristics are highly suggestive of WG. These findings along with clinical or laboratory findings, allow the diagnosis of very limited ophthalmic WG in the absence of systemic involvement.

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