Pigmented ocular fundus lesions and APC mutations in familial adenomatous polyposis

Orbital osteomas associated with Gardner's syndrome: a case presentation and review of literature

Gardner syndrome (GS) is a rare genetic disorder characterized by numerous intestinal colon polyps with various extraintestinal manifestations. Osteomas are a known extracolonic manifestation of GS and can affect the orbit, as seen in our patient, as well as 13 other cases documented in literature. Excision of large orbital osteomas can be successful with a multi-disciplinary approach as presented in this article. Ophthalmologists can even be the first to diagnose GS, usually via the presence of congenital hypertrophy of the retinal pigment epithelium (CHRPE) lesions. Untreated, 100% of colon polyps will transform into cancer, thus it is important to be aware of this rare syndrome with ophthalmic manifestations and screen patients with osteomas for GS.

Congenital Hypertrophy of the Retinal Pigment Epithelium (CHRPE) as a Screening Marker for Familial Adenomatous Polyposis (FAP): Systematic Literature Review and Screening Recommendations

Purpose

Familial adenomatous polyposis (FAP) has an almost 100% colorectal cancer risk warranting early detection in gene carriers. This study presents congenital hypertrophy of the retinal pigment epithelium (CHRPE) as a highly specific phenotypical marker for FAP that can be used in screening at-risk individuals. Screening recommendations including morphological subclassification were formulated with supporting literature.

Methods

A systematic literature review with a comprehensive search strategy was conducted using online databases. Manual searches of bibliographies and reference lists were also performed. Studies meeting inclusion criteria were graded with respect to their hierarchy of evidence and strength of recommendations according to the National Health and Medical Research Council (NHMRC) guidelines of Australia.

Results

Almost 4500 participants were analysed across 28 included studies. The mean specificity of CHRPE as a phenotypical screening marker of FAP was 89% (standard deviation (SD); 14) with a mean sensitivity of 79% (SD; 8). The mean prevalence of CHRPE amongst FAP participants; at-risk participants were found to be 76% (SD; 24) and 37% (SD; 21) respectively. Bilateralism and multiple lesion number ≥3 are features highly specific for FAP.

Conclusion

CHRPE was found to be a non-invasive, rapid, early phenotypical screening marker of FAP. Clinical recognition further allows increased gene analysis efficiency. The absence of CHRPE alone cannot exclude FAP. Our screening recommendations provide guidance to clinicians on evidence based CHRPE assessment. We would advocate inclusion of ocular examinations as part of a three-pronged approach, along with endoscopy and genetic testing, for efficient, timely FAP assessment in at-risk individuals.

[Retinal tumors in adults: Part 2 nonvascular tumors of retina and retinal pigment epithelium]

Retinal tumors are a heterogeneous group of congenital and acquired lesions. In the second part of the article retinocytic and glial cell tumors of the retina, tumors of the retinal pigment epithelium, malignant tumors, such as lymphomas and metastases are presented. In benign and malignant tumors visual symptoms, such as exudative retinal detachment occur, which often lead to irreversible visual impairments. Because visual symptoms are often a manifestation of systemic diseases, the ophthalmologist plays an important role in the accurate and early diagnosis of retinal tumors. This article reviews the most important clinical and diagnostic features of retinal tumors in adults, the systemic associations and the literature on currently available treatment strategies.

Familial Adenomatous Polyposis Syndrome: An Update and Review of Extraintestinal Manifestations

CONTEXT.—

Familial adenomatous polyposis (FAP) is a rare genetic disorder with autosomal dominant inheritance, defined by numerous adenomatous polyps, which inevitably progress to colorectal carcinoma unless detected and managed early. Greater than 70% of patients with this syndrome also develop extraintestinal manifestations, such as multiple osteomas, dental abnormalities, and a variety of other lesions located throughout the body. These manifestations have historically been subcategorized as Gardner syndrome, Turcot syndrome, or gastric adenocarcinoma and proximal polyposis of the stomach. Recent studies, however, correlate the severity of gastrointestinal disease and the prominence of extraintestinal findings to specific mutations within the adenomatous polyposis coli gene (APC), supporting a spectrum of disease as opposed to subcategorization. Advances in immunohistochemical and molecular techniques shed new light on the origin, classification, and progression risk of different entities associated with FAP.

OBJECTIVE.—

To provide a comprehensive clinicopathologic review of neoplastic and nonneoplastic entities associated with FAP syndrome, with emphasis on recent developments in immunohistochemical and molecular profiles of extraintestinal manifestations in the thyroid, skin, soft tissue, bone, central nervous system, liver, and pancreas, and the subsequent changes in classification schemes and risk stratification.

DATA SOURCES.—

This review will be based on peer-reviewed literature and the authors' experiences.

CONCLUSIONS.—

In this review we will provide an update on the clinicopathologic manifestations, immunohistochemical profiles, molecular features, and prognosis of entities seen in FAP, with a focus on routine recognition and appropriate workup of extraintestinal manifestations.

Diplopia as presenting sign of Turcot syndrome

PURPOSE

To describe a patient with diplopia who was diagnosed with Turcot syndrome.

METHODS

A 10-year-old boy presented with a history of left-sided sixth and seventh nerve palsy. He underwent imaging of the brain and colon, a full ophthalmological and genetic work-up.

RESULTS

A 10-year-old boy was referred with combined left-sided sixth and seventh nerve palsy since 1 month without symptoms of raised intracranial pressure. BCVA was 6/6 in both eyes. Fundoscopy revealed bilateral, multiple, oval pigmented ocular fundus lesions (POFLs) in the 4 quadrants. These POFLs, together with the cranial nerve palsies raised the suspicion of Turcot syndrome, a familial neoplasia syndrome characterized by familial colorectal cancer and tumours of the central nervous system. Urgent MRI scan of the brain and stereotactic biopsy showed a primitive neuroectodermal tumour (PNET) at the pons. Coloscopy revealed multiple polyps. DNA analysis of the APC gene confirmed the clinical diagnosis of Turcot syndrome. The PNET was treated with combined radio- and chemotherapy. The patient underwent a prophylactic total colectomy as virtually all patients develop a carcinoma of the colorectal region if left untreated.

CONCLUSIONS

Although strabismus is not, diplopia in childhood is rare and seldom innocuous. It requires a prompt and thorough diagnostic evaluation, including thorough, dilated fundoscopy. The presence of POFLs combined with neurological symptoms suggestive of a brain tumour should alert the clinician of the possibility of Turcot syndrome. Recognition of this rare syndrome can lead to earlier diagnosis, which is vital for appropriate surveillance and early surgical intervention of the highly frequent neoplasias in Turcot Syndrome.

Pigmented Lesions of the Retinal Pigment Epithelium

: The primary eye care practitioner assumes an important role in clinical decisions involving the differentiation between malignant and nonmalignant pigmented lesions. A misdiagnosis may have profound consequences on patient management and visual or life prognosis. However, information on these lesions, particularly their appearance using advanced imaging, is fragmented throughout the literature. The purpose of this review is to describe these features in detail, so that the implications of this information on clinical practice are more readily apparent. Clinically relevant descriptions of pigmented lesions of the retinal pigment epithelium using traditional and advanced imaging modalities in the literature were collated and integrated with findings from patients seen at the Centre for Eye Health. The information was then organized and tabulated. Finally, a flow diagram was created to be used as a clinical reference in the differential diagnosis of pigmented lesions of the retinal pigment epithelium.

Congenital hypertrophy of retinal pigment epithelium (CHRPE) in patients with familial adenomatous polyposis (FAP); a polyposis registry experience

BACKGROUND

Familial Adenomatous Polyposis (FAP) is an autosomal dominant condition giving rise to multiple adenomatous polyps in the colon which invariably become malignant by the fourth decade. Congenital hypertrophy of retinal pigment epithelium (CHRPE) is one of its extra intestinal manifestations early in childhood seen, present in 90% of FAP population and is easy to detect.

FINDINGS

Patients diagnosed with FAP and at risk first degree family members were screened for CHRPE using a slit lamp and indirect ophthalmoscopy. The retina of 17 diagnosed FAP patients and 13 individuals at risk were examined. The site and size of CHRPE lesions were documented. Thirteen (76%) of 17 FAP patients (male-10, female - 7, median age - 30 years; range 15-55 years) had CHRPE lesions; seven (54%) had bilateral CHRPE lesions and six (46%) had unilateral lesions. A single lesion was detected in 6 (46%) while 7 (54%) patients had multiple lesions. Of 13 at risk individuals (7- male, female-6 ; median age 34; range 16-52 years), one was positive for CHRPE and 12 were free of retinal lesions. The sensitivity of the presence of a CHRPE lesion in association with colonic polyps in FAP was 76%, specificity 92%, positive predictive value 93%, and negative predictive value 75%.

CONCLUSIONS

This study found a high sensitivity and specificity for a CHRPE lesion to be associated with colonic polyps of FAP and hence a useful screening method in a burdened health-care system. The method is minimally invasive and simple and would be of particular value in screening children at risk for FAP.

A potential life-saving diagnosis--recognizing Turcot syndrome

A previously healthy 9-year-old girl presented with ataxia, headaches, and nausea of 1 month's duration. Magnetic resonance imaging demonstrated a large posterior fossa mass. Posterior segment examination revealed pigmented ocular fundus lesions (POFLs), which included cometoid dark lesions with depigmented tails and smaller, dark midperipheral lesions. The patient underwent resection for a medulloblastoma. Because of these specific retinal lesions in combination with her medullobastoma, a diagnosis of Turcot syndrome was made and subsequently confirmed by genetic testing. Turcot syndrome is one of the familial adenomatous polyposis (FAP) syndromes. This diagnosis may be life-saving because 100% of FAP patients develop colon cancer that can be cured only early with timely colectomy.

A unique presentation of grouped congenital hypertrophy of the retinal pigment epithelium

PURPOSE

To describe a unique presentation of grouped congenital hypertrophy of the retinal pigment epithelium (CHRPE) and to review the clinical features which differentiate grouped CHRPE from the pigmented ocular fundus lesions (POFLs) associated with familial cancer syndromes.

METHODS

Report of a case.

RESULTS

A 28-year-old asymptomatic, Caucasian female demonstrated multiple small, flat, dark brown to black clusters of retinal pigment epithelium (RPE) hypertrophy on dilated fundus examination of both eyes. These plaque-like lesions were circumferential along the peripheral fundus and were associated with smaller foci of pigmentation oriented towards the posterior pole. The appearance was consistent with grouped pigmented CHRPE. A unique, co-existing feature was the presence of non-pigmented, punctate lesions located within the maculae suggestive of grouped non-pigmented CHRPE. Fluorescein angiography demonstrated persistent hypofluorescence correlating with the clinically observed areas of hyperpigmentation and hypopigmentation.

CONCLUSIONS

The combination of both pigmented and non-pigmented lesions occurring in the same individual with grouped CHRPE is rare. It is important to distinguish grouped CHRPE lesions from the POFLs associated with familial cancer syndromes.

Germinoma presenting as a fourth cranial nerve palsy in a patient with adenomatous polyposis coli (APC) gene mutation

A 17-year-old boy with adenomatous polyposis and a history of an adenomatous polyposis coli (APC) gene mutation (IVS13(-2) A>G) presented for evaluation of vertical, binocular diplopia. Examination was suggestive of a fourth (trochlear) nerve palsy. A history of headaches was elicited and led to further investigation with neuroimaging, which identified a germinoma in the tectal plate and secondary hydrocephalus. We report the clinical, radiological, and histopathological findings of this patient, who to our knowledge is the first reported case of a germinoma occurring in association with adenomatous polyposis.

Congenital hypertrophy of the retinal pigment epithelium (CHRPE) in familial colorectal cancer

BACKGROUND AND AIM

Congenital hypertrophy of the retinal pigment epithelium (CHRPE) is a pigmented fundus lesion associated with familial adenomatous polyposis (FAP). CHRPE prevalence has been reported to be increased in subjects with familial or sporadic non-polyposis colorectal cancer (CRC), suggesting that some individuals with non-polyposis CRC have an attenuated form of FAP. Other studies have not confirmed these clinical observations and have failed to identify mutations in the gene responsible for FAP, but the reason for the discrepancy in relation to CHRPE prevalence has not been resolved. We determined the prevalence of CHRPE in subjects without CRC (negative control cohort), subjects with FAP (positive control cohort), and subjects with familial non-polyposis CRC (test cohort).

METHOD

A cohort study consisting of 37 negative control subjects, 9 positive control subjects with documented APC gene mutations, and 36 test subjects with familial non-polyposis CRC but no identified pathogenic APC gene mutation. The diagnosis of hereditary non-polyposis colon cancer was excluded in the test cohort by testing for microsatellite instability in tumour tissue.

RESULTS

None of the 37 people in the negative control group had CHRPE. Five of nine (56%) patients with FAP had multiple CHRPE lesions. None of the 36 subjects in the test cohort had CHRPE lesions.

CONCLUSIONS

Ophthalmoscopy may contribute to risk assessment in families with FAP but not in familial non-polyposis CRC. Care must be exercised when interpreting pigmented fundus lesions because 8-13% of subjects in each of the cohorts had pigmented retinal lesions that were not CHRPE. Bilateral lesions and lesions with a depigmented halo were the hallmarks of CHRPE associated with FAP.

Selected pigmented fundus lesions of children

BACKGROUND

Ocular cells that accumulate melanin pigment are derived from 1 of 2 sources, the optic vesicle or the neural crest. Migration and distribution of pigment containing cells may go awry during fetal development or these cells may be altered before or after birth either by local or systemic stimuli. Specific recognition patterns of pigment distribution often exist and may relate directly to a single disease process.

METHODS

Records of pediatric patients with disorders of pigment distribution in the ocular fundi who had been examined by the author were reviewed.

RESULTS

Five disorders with recognizable patterns of retinal pigment epithelium (optic vesicle derivation) disturbance (congenital hypertrophy of the retinal pigment epithelium, Gardner syndrome, chronic granulomatous disease, preserved para-arteriole retinal pigment epithelium in (autosomal-recessive) retinitis pigmentosa, and combined hamartoma of the retina and retinal pigment epithelium), and 5 disorders of cells originating from the neural crest (choroidal nevi, choroidal melanoma, melanocytoma, ocular melanosis, and oculodermal melanosis), were selected for illustration and discussion.

CONCLUSIONS

These arbitrarily selected groups of disorders affect or involve patterns of pigment deposition in the ocular fundus. These patterns are recognizable and distinguishable one from another but have different implications for treatment and follow-up. Progress in recognizing distinguishing characteristics, diagnostic implications, understanding, and treatment of these disorders during the past 40 years is compared and contrasted between the 2 groups.

[Osteomatous jaw lesions in familial adenomatous polyposis]

The first aim of this study is to assess the frequency of osteomatous jaw lesions in patients with a diagnosis of familial adenomatous polyposis (FAP), and a group of FAP-relatives from the FAP registry of Majorca (Balearic Islands, Spain). The second aim is to study the predictive significance of osteomatous jaw lesions in families with FAP. The study included forty-two people. Twenty-five patients and seventeen relatives. All individuals underwent pantomography. Osteomatous jaw lesions were diagnosed in 68% of FAP-patients, and 6% of FAP-relatives. The difference was statistically significant (p < 0.001). The sensitivity was 68%, the specificity 94% and positive predictive value 94%. This frequency of osteomatous jaw lesions agree with previous studies of FAP-patients (57-82%), but differ from these of the previous studies of FAP-relatives (16-18%). The available method detect APC (adenomatous polyposis coli) gene mutations in 48-82% of FAP families. In the families without detected mutation, non-informative study or non-available study, the screening is based in seriated sigmoidoscopy and study of the extraintestinals lesions of the FAP syndrome. The frequency of osteomatous jaw lesions in FAP-patients is greater than the observed in FAP-relatives (p < 0.001). Osteomas in families with FAP are of predictive significance.

Diagnosis and management of hereditary colon cancer

Colorectal cancer is the third leading cause of cancer and the second leading cause of cancer death in the United States. About 130,000 new cases are diagnosed each year in North America, and 56,600 persons die annually from this disease. Approximately 5% of patients with colorectal cancer have clearly defined inherited syndromes such as familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer. These conditions are well described both genetically and phenotypically, and are characterized by autosomal dominant inheritance, high penetrance, and high risk of colorectal cancer. We review the current recommendations for the diagnosis and management of these two hereditary forms of colorectal cancer.

Genetic testing for familial adenomatous polyposis

Familial adenomatous polyposis (FAP, Mendelian Inheritance in Man number *175,100 [edited by Victor A. McKusick], accessible on line under http:¿www3.ncbi.nlm.nih.gov/htbin-post/ Omim/dispmim?175100) is a dominantly inherited colorectal cancer predisposition syndrome. The designation Gardner Syndrome is used for phenotypic variants of FAP with additional extracolonic symptoms. After the adenomatous polyposis coli (APC) gene was identified with the help of positional cloning strategies in 1991, it became evident that inactivation of this tumor suppressor is based on loss of carboxyterminal protein-protein interaction domains. Identification of multiple molecular constituents binding to the distal half of the APC protein revealed its crucial involvement in wnt-signaling. Because the spectrum of mutations is predominated by small insertions and deletions, nonsense-, and splice-site mutations, a prescreening procedure is employed for the identification of germinal mutations in FAP patients that relies on in vitro synthesis of APC gene products, an approach also known under the acronym PTT (protein truncation test). Absence of nonsense-mediated mRNA decay of mutated APC transcripts allows the application of a cDNA-based coupled in vitro transcription/translation reaction for exons 1 to 14. Examination of four overlapping fragments from genomic DNA of probands reveals stops in the large APC exon 15, encompassing more than 6500 base pairs. Using this procedure, mutations causing the disease will be identified in about 80% of FAP patients. In the other cases of clinically manifest FAP, evidence exists that reduction of the steady state level of APC protein as a result of transcriptional silencing or large genomic deletions could provide for the clinical phenotype. Although some genotype-phenotype correlations have been described, exceptions from the rule have been reported, that is, for CHRPE. Modifier genes for the development of extracolonic manifestations are currently still enigmatic. Knowledge of such genes would essentially contribute to a better presymptomatic treatment of FAP patients.

Fundus lesions of adenomatous polyposis

Congenital hypertrophy of the retinal pigment epithelium (CHRPE) is the most frequent extraintestinal manifestation of familial adenomatous polyposis. Present in 70% of families with familial adenomatous polyposis, CHRPE is a highly reliable and early marker of the disease. Studies over the past 5 years have addressed the histologic characteristics of the pigmented fundus lesions, the definition of universal positive fundus criteria, and mostly the genotype-phenotype correlation. Indeed, the position of the mutation site of the APC (adenomatous polyposis coli) gene on chromosome 5 influences the retinal expressivity because CHRPE is present only if the mutation is located between exons 9 and 15. In CHRPE-positive families, fundus examination is simple, noninvasive, reproducible, inexpensive, and allows early detection of the mutant gene carriers. Knowing the CHRPE status of patients in a family with familial adenomatous polyposis helps to identify constitutional APC mutations. The combination of genetic analysis and fundus examination offers a 100% diagnostic predictability.

Cloning and characterization of a secreted frizzled-related protein that is expressed by the retinal pigment epithelium

The Wnt/frizzled cell signaling pathway has been implicated in the determination of polarity in a number of systems, including the Drosophila retina. The vertebrate retina develops from an undifferentiated neuroepithelium into an organized and laminated structure that demonstrates a high degree of polarity at both the tissue and cellular levels. In the process of searching for molecules that are preferentially expressed by the vertebrate retinal pigment epithelium (RPE), we identified secreted frizzled-related protein 5 (SFRP5), a member of the SFRP family that appears to act by modulating Wnt signal transduction. SFRP5 is highly expressed by RPE cells, and is also expressed in the pancreas. Within the retina, the related molecule SFRP2 is expressed specifically by cells of the inner nuclear layer. Thus, photoreceptors are likely to be bathed by two opposing gradients of SFRP molecules. Consistent with SFRP5 's postulated role in modulating Wnt signaling in the retina, it inhibits the ability of Xwnt-8 mRNA to induce axis duplication in Xenopus embryos. The human SFRP5 gene consists of three coding exons and it maps to chromosome 10q24.1; human SFRP2 maps to 4q31.3. Based on the biology and complementary expression patterns of SFRP2 and SFRP5, we suggest that they may be involved in determining the polarity of photoreceptor, and perhaps other, cells in the retina.

Ocular findings in familial adenomatous polyposis

BACKGROUND

Retinal pigment epithelium (RPE) lesions are predictive congenital phenotypic markers for familial adenomatous polyposis (FAP). This prospective screening study aims at assessing the incidence and significance of these lesions in FAP patients and their family members.

METHODS

Sixty-two members from three families including five patients with the diagnosis of FAP have been ophthalmologically surveyed. All RPE lesions were documented with fundus photography and fluorescein angiography was performed in 13 subjects. Sigmoidoscopy and/or radiological examination were performed annually in 9 family members with typical RPE lesions during 4 years to allow early diagnosis of FAP.

RESULTS

Typical RPE lesions were present in five FAP patients and 15 family members. Telangiectatic dilatations in the retinal periphery with small dot-like hemorrhages were detected in 6 subjects from 3 families These lesions were particularly evident on fluorescein angiography. Annual colon analysis showed polyps in 3 out of 9 subjects who were positive for RPE lesions.

CONCLUSION

RPE lesions are valuable as a clinical marker in predicting FAP. The co-existing peripheral vascular alterations which have not been reported before, are probably related to FAP.