Phenotypic variation in hereditary nonpolyposis colon cancer syndrome. Association with infiltrative fibromatosis (desmoid tumor)

3' Mutation of the APC gene and family history of FAP in a patient with apparently sporadic desmoid tumors

Desmoid tumors may occur sporadically or as part of the extraintestinal manifestations of familial adenomatous polyposis. Different phenotypes have been described and some genotype-phenotype correlations have been raised, associated with different sites of germline mutations in the adenomatous polyposis coli (APC) gene. We report on a 42-year-old woman ascertained for a large desmoid tumor of the anterior chest wall with pleural involvement, which persistently recurred despite a decade of treatment including hormone therapy, chemotherapy, and surgery. Spontaneous disappearance of the tumor was later noted after 1 year without any treatment and confirmed after 4 years of regular follow-up. Repeated colonoscopies were normal in the proband and DNA sequencing showed a frameshift mutation due to a single adenosine deletion at position 5772 (codon 1924). This mutation, located in the exon 15 at the 3' end of the APC gene, leads to an unusual and late onset phenotype. The pedigree revealed other isolated or familial adenomatous polyposis-associated cases of desmoid tumors. This family report shows that a molecular analysis of the APC gene should be performed in familial desmoid tumors for accurate genetic counseling and follow-up.

Genetic testing for germline mutations of the APC gene in patients with apparently sporadic desmoid tumors but a family history of colorectal carcinoma

PURPOSE

Desmoid tumors, also known as aggressive fibromatosis, occur with an incidence of 10 to 15 percent in patients affected by familial adenomatous polyposis, an autosomal inherited disease caused by germline mutations in the APC gene. However, sporadic forms with no hereditary background exist. The aim of this study was to find out whether there are APC germline mutations in apparently sporadic desmoid tumor patients without clinical or familial signs of familial adenomatous polyposis but with a family history of colorectal carcinoma in at least one family member.

METHODS

Genomic DNA and mRNA were isolated from peripheral blood leukocytes of index patients of eight nonrelated families. Mutation screening was performed using reverse transcriptase polymerase chain reaction-based protein truncation test for APC exons 1-14. The large APC exon 15 was scrutinized by the protein truncation test of four overlapping genomic fragments. Additionally, genomic DNA from five desmoid tumors was analyzed for loss of heterozygosity at D5S346 close to the APC locus.

RESULTS

No translational stop mutations typical for familial adenomatous polyposis could be found in the APC gene in any of the analyzed blood samples from the desmoid tumor patients. Additionally, no loss of heterozygosity at D5S346 was found in four of five desmoids; one tumor was not informative.

CONCLUSIONS

These results may suggest that patients with sporadic desmoids and no clinical signs of familial adenomatous polyposis detected on careful examination, esophagogastroduodenoscopy, and complete colonoscopy do not need to be tested routinely for germline mutations of the APC gene. However, as large studies dealing with this problem are absent, it might be more time and cost effective to perform an APC mutational analysis instead.

Analysis for phenotype of HNPCC in China

AIM: The aims of this study were to identify the clinicopathological features of Chinese HNPCC families and to evaluate the value of criteria for suspected HNPCC (sHNPCC) in clinical diagnosis.

METHODS: According to the follow-up records, 54 HNPCC families (including 12 ICG-HNPCC families and 42 sHNPCC families) were screened out from patients with colorectal cancers (CRCs), operated upon in 2^nd Affiliated Hospital of Zhejiang University from 1984 to 2001. Clinical data of probands and tumor spectrum in these families were listed and analyzed.

RESULTS: (1) Mean age, proportion of colonic cancer, poorly differentiated cancer, multiple CRCs and Dukes’ A+B of the probands in ICG-HNPCC and sHNPCC kindred were 39 ys and 47.5 ys, 75% and 62%, 0 and 12.8%, 16.7% and 14.3%, 58.3% and 81%, respectively. Compared with sporadic colorectal cancers, probands from ICG-HNPCC and sHNPCC families were obviously different at age of onset (P = 0.025 and 0.031), tumor location (P = 0.001 and 0.000), differentiation (P = 0.002 and 0.011) and development of multiple tumors (P = 0.014 and 0.002). (2) A total of 178 malignant neoplasms were found in 54 HNPCC families, including 139 colorectal cancers. Besides of colorectal cancer, extracolonic tumors occurred in stomach, endometrium, hepatobiliary system, and so on (8 gastric cancers, 6 endometrial cancers, 6 hepatobiliary system cancers and 19 others) can also be seen in Chinese ICG-HNPCC and sHNPCC families.

CONCLUSION: (1) Chinese HNPCC families have specific clinicopathological features, such as early onset, predilection for the involvement of colon, tendency of multiple CRCs, development of extracolonic tumors and well differentiation. (2) The criteria for suspected HNPCC is useful in clinical diagnosis and management of HNPCC.

Extra-abdominal desmoid fibromatosis: two familial cases with synchronous and metachronous multicentric hyalinizing nodules

AIMS

Extra-abdominal desmoid fibromatosis is an uncommon tumour. We present here two exceptional familial cases of extra-abdominal desmoid fibromatosis, one of which was synchronous and metachronous.

METHODS AND RESULTS

The first patient was a 37-year-old woman who had noted a tumour growing on the dorsum of her right foot when she was 12 years old. She underwent excision of the tumour but in the following year the tumour recurred locally and grew into multiple nodules. Subsequently, multicentric tumours appeared in her knee, distal and posterior aspects of her thigh, right back and right anterior shoulder. Polyostotic fibrous dysplasia of the femur and cranium was found on radiological examination. The second patient was a 74-year-old man, the uncle of the first patient. He underwent an excisional operation of a tumour on the internal malleolus surface of his fibula when he was 46 years old. The tumour recurred 7 years later and was excised. His post-operative course has been uneventful. The histology of the primary and recurrent tumours was distinctive and consistently showed hyalinizing scar-like features.

CONCLUSIONS

Familial cases of extra-abdominal desmoid fibromatosis with extensive multicentric lesions and distinctive hyalinizing scar-like features are described. Recently, attenuated familial adenomatous polyposis with familial desmoid fibromatosis has been recognized, and familial desmoid fibromatosis without adenomatous polyposis may also be one of its variants. Although the present cases have no history of colon polyposis or carcinoma, monitoring of the intestinal tract would seem to be indicated.

Gardner-associated fibromas (GAF) in young patients: a distinct fibrous lesion that identifies unsuspected Gardner syndrome and risk for fibromatosis

Gardner syndrome (GS), caused by mutations in the adenomatous polyposis coli (APC) gene, is characterized by polyposis coli, osteomas, and various soft-tissue tumors. If undetected or untreated, virtually all patients develop colonic carcinoma at a young age. Early detection, while essential, can be difficult because of attenuated phenotypes or spontaneous mutations. We present the clinicopathologic features of 11 identical fibromatous lesions that we have termed Gardner-associated fibroma (GAF), which not only appear to be a part of the spectrum of lesions associated with GS but, in some cases, represent the sentinel event leading to its detection. The GAFs occurred in 11 patients (5 boys and 6 girls; age range, 3 months-14 years), were solitary (n = 7) or multiple (n = 4), and occurred in the superficial and deep soft tissues of the paraspinal region (n = 7), back (n = 3), face (n = 2), scalp (n = 2), chest wall (n = 2), thigh (n = 1), neck (n = 1), and flank (n = 1). Histologically, GAFs resemble nuchal-type fibromas (NFs), consisting of thick, haphazardly arranged collagen bundles between which are found occasional bland fibroblasts, and having margins that frequently engulf surrounding structures including adjacent fat, muscle and nerves. After surgical excision, four patients developed recurrences that were classic desmoid fibromatoses (DFs). In one patient with multiple GAFs, one lesion had the features of GAF and DF in the absence of surgical trauma. A family history of GS or polyposis (n = 6) or DF (n = 1) was known at the time of surgery in seven patients. In three patients, the diagnosis of GAF resulted in the diagnosis of unsuspected APC in older family members, with the detection of an occult colonic adenocarcinoma in one parent. In the family of the remaining patient, no stigmata of GS were present. Genetic analysis of this child was performed to investigate the presence of a spontaneous (new) mutation; however, no abnormalities were detected. The significance of GAF is that it serves as a sentinel event for identifying GS kindreds, including those with a high risk for the development of DF, and it may potentially identify children with spontaneous mutations of the APC gene. Because NFs and GAFs resemble one another, we suggest that a subset of NF occurring in multiple sites, unusual locations, or children may be GAF.

Extracolonic features of familial adenomatous polyposis in patients with sporadic colorectal cancer

We have investigated the occurrence of attenuated extracolonic manifestations (AEMs) of familial adenomatous polyposis (FAP) in patients with non-polyposis colorectal cancer. In a prospective case-control study, we observed that significantly more colorectal cancer patients exhibited AEM than did age and sex-matched controls (19.5% vs 7.5%, P < 0.004). However patients with AEMs do not have occult FAP, as we found no heterozygous adenomatous polyposis coli (APC) gene mutations despite extensive analysis of constitutional DNA. Genome-wide DNA replication errors (RERs) occur in a proportion of colorectal cancers, particularly right-sided lesions and in almost all tumours from hereditary non-polyposis colorectal cancer (HNPCC) patients. As AEMs have been reported in familial colon cancer cases, we investigated the relationship of AEMs to tumour RER phenotype. There was indeed an excess of AEMs in patients with right-sided tumours (30.2% of 53 patients vs 14.7% of 116 patients, P < 0.03) and in those with RER tumours (3 out of 12 patients with RER tumours vs none out of 21 patients with non-RER tumours, P < 0.05). Two patients with AEM were from HNPCC families compared with none of those without AEM (P < 0.05). The association of AEMs with colorectal cancer is intriguing, and we speculate that it may be a manifestation of mutational mosaicism of the APC gene, perhaps associated with a constitutional defect in DNA mismatch pair.

Hereditary nonpolyposis colorectal cancer (Lynch syndrome). An updated review

BACKGROUND

Hereditary nonpolyposis colorectal cancer (HNPCC) dates to Aldred Warthin's description of Family G a century ago. The phenotype features an excess of early onset colorectal carcinoma (CRC) with a propensity to involve the proximal colon, and a variety of extracolonic cancers, particularly carcinoma of the endometrium, ovary, stomach, small bowel, ureter, and renal pelvis. The recent discovery that HNPCC patients carry germline mutations in DNA mismatch repair genes has engendered great interest in the syndrome.

METHODS

This is a description of HNPCC based on the authors' experience with more than 170 families and a review of the world literature.

RESULTS

This review describes the genotypic and phenotypic features of HNPCC. The distinctive natural history of the syndrome is discussed in light of the recent discovery that ineffective DNA mismatch repair is the principal abnormality in affected individuals.

CONCLUSIONS

Clinical and molecular genetic knowledge about HNPCC is now available to physicians, and should enable them to provide highly targeted surveillance and management for patients with a high cancer risk. Genetic counseling can prove lifesaving. The study of HNPCC will likely contribute to knowledge about the causes and control of common forms of cancer in the general population.

Mesenteric fibromatosis in Crohn's disease

We have seen two patients with Crohn's disease and mesenteric fibromatosis, the least common form of desmoid tumor. Although both gastrointestinal and nongastrointestinal tumors are relatively common in Crohn's disease, this type of tumor has not been seen in > 1,650 patients operated on for this condition. As the only common factor in the two male patients discussed in this article was previous intestinal resections, surgical trauma may be a predisposing factor in the occurrence of these desmoid tumors. We will continue to search for other examples in patients with Crohn's disease.

Mutator genes and mosaicism in colorectal cancer

Recent studies have shed light on the role of defective DNA mismatch repair in human cancer. An elevated mutation rate associated with mismatch repair deficiency has been demonstrated in the germline and normal tissue from patients with hereditary non-polyposis colorectal cancer and transgenic animals respectively. Thus mismatch repair deficiency may permit the accumulation of mutations in cancer genes that do not confer growth advantage. This represents one potential mechanism for the induction of mutational mosaicism in humans.

Molecular genetic analysis of exons 1 to 6 of the APC gene in non-polyposis familial colorectal cancer

Familial adenomatous polyposis coli is caused by constitutional mutations in the APC gene. The hallmark of familial adenomatous polyposis coli is the presence of numerous (> 100) colorectal polyps, but mutations in the 5' end of the APC gene have been associated with familial colorectal cancer without florid polyposis. Although familial adenomatous polyposis coli accounts for only a minority of familial colorectal cancer cases, we hypothesised that APC mutations which were not associated with florid polyposis might make a significant contribution to nonpolyposis familial colorectal cancer. To investigate this possibility, we analysed 40 unrelated patients with familial colorectal cancer without classical familial adenomatous polyposis coli for mutations in exons 1 to 6 (codons 1 to 243) of the APC gene. No mutations were detected, but a C-->T polymorphism at nucleotide 333 (Arg-->Trp at codon 99) was identified. No 5' APC mutations were detected in two patients with desmoid tumours and a family history of colorectal cancer and polyps. We conclude that mutations in exons 1 to 6 of the APC gene are infrequent in patients with familial colorectal cancer who do not have many colorectal polyps.

Tumour spectrum in hereditary non-polyposis colorectal cancer (HNPCC) and in families with "suspected HNPCC". A population-based study in northern Italy. Colorectal Cancer Study Group

Hereditary non-polyposis colorectal cancer (HNPCC or Lynch syndrome) is characterized by the early onset of colorectal neoplasms, frequently localized in the right colon, increased occurrence of multiple primaries, vertical transmission and aggregation of tumours in families in accordance to a Mendelian dominant type of inheritance. The syndrome accounts for approximately 5% of all colorectal cancers. The purpose of the present study was to describe the tumour spectrum and the most relevant clinical features of 28 kindreds with HNPCC, classified according to the guidelines of the International Collaborative Study Group, and of 61 "suspected" HNPCC. These families were observed during a 6-year registration of colorectal neoplasms in a health-care district of Northern Italy. Colorectal cancer was by far the most frequent malignancy; gastric cancer was the second. Uterine carcinoma was only slightly more frequent than expected. Lung- and breast-tumour rates were lower than expected. Cancer distribution in the large bowel showed that about two fifths of the tumours developed in the right colon. The occurrence of cancer before the age of 50 to 60 was much more frequent in HNPCC. Multiple tumours developed in 25 patients with HNPCC and in 32 with "suspected" HNPCC. Pancolonoscopy remains the procedure of choice for surveillance; other examinations, such as gastroscopy, gynaecological investigations, urography and cholangiography, are suggested only to selected families. One of the main features of the study was the inclusion of 61 "suspected" HNPCC, a heterogeneous group of families which nonetheless deserves careful follow-up.