Cribriform-morular variant of papillary thyroid carcinoma: a pathological and molecular genetic study with evidence of frequent somatic mutations in exon 3 of the beta-catenin gene

Cribriform-morular variant of papillary thyroid carcinoma displaying poorly differentiated features

Cribriform-morular variant of papillary thyroid carcinoma (CMVPTC) usually occurs in the setting of familial adenomatous polyposis (FAP) although it can rarely arise sporadically. Poorly differentiated thyroid carcinoma (PDTC) is a follicular cell-derived neoplasm with more aggressive behavior than well-differentiated carcinomas such as CMVPTC. We report the case of a 35-year-old woman without FAP history who presented a left neck mass and complained of back pain. Imagiological examinations revealed a nodule in the left lobe of thyroid and multiple nodular lesions in the bone and lungs suggestive of metastases. The patient was submitted to total thyroidectomy and radioactive iodine. The tumor was composed of CMVPTC and PDTC components that shared the same somatic APC gene mutation (p.Cys520Tyr_fsX534). Besides this mutation, no CTNNB1, BRAF, N-RAS, and H-RAS gene mutations were detected in any of the 2 components. To the best of our knowledge, this is the first report of a sporadic CMVPTC with transformation into PDTC. Although the majority of CMVPTCs carry an indolent clinical outcome, the coexistence of poorly differentiated areas may justify the aggressiveness of the CMVPTC reported here.

Cribriform-Morular Variant of Papillary Thyroid Carcinoma in an 8-Year-Old Girl

The description of the histological features and the immunohistochemical and molecular analyses of a case of cribriform-morular variant of papillary thyroid carcinoma in an 8-year-old girl with a family history of adenomatous polyposis is presented. The neoplasm was multifocal and bilateral, with a mixed pattern of solid, trabecular, and morular areas. The neoplasm showed angioinvasive behavior, extracapsular infiltration with extension to the perythyroidal muscles, and lymph node metastases. Tumor cells were positive for CAM 5.2, cytokeratins 5/6, TTF-1, HBME-1, galectin-3, and β-catenin. In addition, the molecular tests did not reveal BRAF mutations, RET/PTC rearrangement, APC mutation, or KRAS mutation.

Role of the wnt pathway in thyroid cancer

Aberrant activation of Wnt signaling is involved in the development of several epithelial tumors. Wnt signaling includes two major types of pathways: (i) the canonical or Wnt/β-catenin pathway; and (ii) the non-canonical pathways, which do not involve β-catenin stabilization. Among these pathways, the Wnt/β-catenin pathway has received most attention during the past years for its critical role in cancer. A number of publications emphasize the role of the Wnt/β-catenin pathway in thyroid cancer. This pathway plays a crucial role in development and epithelial renewal, and components such as β-catenin and Axin are often mutated in thyroid cancer. Although it is accepted that altered Wnt signaling is a late event in thyroid cell transformation that affects anaplastic thyroid tumors, recent data suggest that it is also altered in papillary thyroid carcinoma (PTC) with RET/PTC mutations. Therefore, the purpose of this review is to summarize the main relevant data of Wnt signaling in thyroid cancer, with special emphasis on the Wnt/β-catenin pathway.

Familial thyroid cancer: a review

Thyroid carcinomas can be sporadic or familial. Familial syndromes are classified into familial medullary thyroid carcinoma (FMTC), derived from calcitonin-producing C cells, and familial non-medullary thyroid carcinoma, derived from follicular cells. The familial form of medullary thyroid carcinoma (MTC) is usually a component of multiple endocrine neoplasia (MEN) IIA or IIB, or presents as pure FMTC syndrome. The histopathological features of tumors in patients with MEN syndromes are similar to those of sporadic tumors, with the exception of bilaterality and multiplicity of tumors. The genetic events in the familial C-cell-derived tumors are well known, and genotype-phenotype correlations well established. In contrast, the case for a familial predisposition of non-medullary thyroid carcinoma is only now beginning to emerge. Although, the majority of papillary and follicular thyroid carcinomas are sporadic, the familial forms are rare and can be divided into two groups. The first includes familial syndromes characterized by a predominance of non-thyroidal tumors, such as familial adenomatous polyposis and PTEN-hamartoma tumor syndrome, within others. The second group includes familial syndromes characterized by predominance of papillary thyroid carcinoma (PTC), such as pure familial PTC (fPTC), fPTC associated with papillary renal cell carcinoma, and fPTC with multinodular goiter. Some characteristic morphologic findings should alert the pathologist of a possible familial cancer syndrome, which may lead to further molecular genetics evaluation.

Familial adenomatous polyposis-rendering a diagnosis based on recognition of an unusual primary thyroid neoplasm

It has been well established in the literature that the cribriform-morular variant of papillary thyroid carcinoma (CMVPTC) has been observed with higher frequency in familial adenomatous polyposis (FAP) patients. In the usual setting, patients with FAP are identified based on their germline mutations and the diagnosis of thyroid neoplasm is made after the FAP diagnosis. We herein report a case in which the recognition of a CMVPTC led to the initial diagnosis of FAP. The histological and clinical features of CMVPTC are reviewed with emphasis on its relationship to FAP.

Our experience of treatment of cribriform morular variant of papillary thyroid carcinoma; difference in clinicopathological features of FAP-associated and sporadic patients

Cribriform-morular variant (CMV) is a comparably rare histological subtype of papillary thyroid carcinoma (PTC). This can be associated with familial adenomatous polyposis (FAP) due to APC gene mutations. In this study, we investigated the difference in the biological characteristics between FAP-associated and sporadic CMV. Between 1991 and 2010, 32 patients with CMV were treated in Kuma Hospital. Thirty-one of these underwent initial surgery for CMV in Kuma Hospital. Twelve patients were FAP-associated and the remaining 19 were sporadic CMV. All patients were female. Tumors of FAP-associated CMV were more frequently multiple than those of sporadic CMV. Patient age and tumor size did not differ between the two groups. Of 12 FAP-associated CMV, 5 were detected by thyroid nodule (thyroid precedent group) and 7 were detected by FAP (polyposis precedent group) as an initial manifestation. Patient age was younger and tumor size was smaller in the polyposis group than in the thyroid nodule group. All patients lacked extrathyroid extension on intraoperative finding and were node-negative on pathological examination. To date, two patients with FAP-associated CMV who initially underwent hemithyroidectomy (one in Kuma Hospital and one in another hospital) showed recurrence to the remnant thyroid during follow-up. None of the patients showed recurrence to other regions or died of carcinoma. Taken together, CMV is considered an indolent disease in our series. FAP-associated CMV showed multiple tumors more frequently than sporadic CMV. Total thyroidectomy is recommended for FAP-associated CMV, but extensive lymph node dissection is not necessary.

The spectrum of papillary thyroid carcinoma variants

Papillary thyroid carcinoma is the most common type of thyroid malignancy. The diagnostic features of these tumors include characteristic nuclear cytology. However, many variants have been reported with different morphology and molecular profiles. Although the vast majority of papillary thyroid carcinomas have an excellent prognosis, some variants of papillary thyroid carcinoma can have a more aggressive course. With this increased attention to papillary thyroid carcinoma variants has come the need to sort out which variants are clinically important and should be recognized by practicing pathologists. The main objectives of this review article are to (1) summarize the gross and histopathologic features of papillary thyroid carcinoma; (2) provide an overview of the subtypes of papillary thyroid carcinoma and their prognosis; (3) discuss established and emerging data on the immunohistochemical findings that are helpful in differential diagnosis; and (4) summarize molecular findings and pathogenesis of these lesions.

Thyroid cancer of follicular cell origin in inherited tumor syndromes

Well-differentiated thyroid cancer accounts for 95% of thyroid malignancies. In contrast to medullary thyroid carcinoma, in which about 25% are familial, only 5% of follicular cell-derived thyroid carcinomas are a component of a familial cancer syndrome. The familial follicular cell-derived tumors or nonmedullary thyroid carcinoma encompass a heterogeneous group of diseases, and are classified into 2 distinct groups: syndromic-associated tumors, occurring in syndromes in which nonmedullary thyroid carcinomas are the predominant tumor encountered, and nonsyndromic tumors, those occurring in tumor syndromes in which thyroid involvement is a minor component. The first group, syndromic-associated tumors, includes phosphase and tensin (PTEN)-hamartoma tumor syndrome/Cowden syndrome, familial adenomatous polyposis/Gardner syndrome, Carney complex type 1, Werner syndrome, and Pendred syndrome. Other syndromes, as McCune Albright syndrome, Peutz-Jeghers syndrome, and Ataxia-teleangiectasia syndrome may be associated with the development of follicular cell-derived tumors, but the link is less established than the above syndromes. The syndromic-associated tumors are the focus of this review. The second group of familial follicular cell-derived tumors syndromes or nonsyndromic tumors, in which nonmedullary thyroid carcinomas are the major findings, include pure familial papillary thyroid carcinoma, with or without oxyphilia, familial papillary thyroid carcinoma with papillary renal cell carcinoma, and familial papillary thyroid carcinoma with multinodular goiter. This review will discuss the clinical and pathological findings of the patients with familial syndrome-associated tumors: PTEN-hamartoma tumor syndrome/Cowden syndrome, familial adenomatous polyposis syndrome, Carney complex type 1, Werner syndrome, and Pendred syndrome.

The cytological, clinical, and pathological features of the cribriform-morular variant of papillary thyroid carcinoma and mutation analysis of CTNNB1 and BRAF genes

BACKGROUND

The cribriform-morular variant of papillary thyroid carcinoma (CMVPTC) is an unusual subtype of papillary thyroid carcinoma. The goal of this study was to determine the clinicopathological features of CMVPTC and whether the tumor can be diagnosed by fine-needle aspiration cytology.

METHODS

We retrospectively analyzed the clinical appearance and pathological findings in five patients with CMVPTC and sequenced exon 3 of CTNNB1 and exon 15 of BRAF in tumor tissue.

RESULTS

All patients were young women, 15-34 years of age at the time of the cancer diagnosis. Preoperative cytological examination showed scattered tall columnar cells, fascicular spindle cells, and cribriform and morular patterns in the fine-needle aspirates of the thyroid from the five patients. Grossly, all tumors were well-circumscribed, solid or cystic. Immunohistochemically, most tumor cells showed nuclear expression of thyroid transcription factor-1, estrogen and progesterone receptors, and p53; cytoplasmic expression of cytokeratins 7 and 19, vimentin, and bcl-2; and cytoplasmic and nuclear accumulation of beta-catenin and galectin-3. There was no expression of thyroglobulin, cytokeratin 5/6, or human mesothelial cell-1. However, among these markers, the morular cells showed only positive immunostaining for beta-catenin, galectin-3, p53, and bcl-2. A CTNNB1 mutation was identified in only one case and no BRAF mutation was found in any of the five cases.

CONCLUSIONS

Taken together, these data suggest that CMVPTC can be diagnosed preoperatively, based on careful cytology examination, and shows unique immunohistochemical findings.

The T1799A BRAF mutation is absent in cribriform-morular variant of papillary carcinoma

CONTEXT

Cribriform-morular variant of papillary thyroid carcinoma (CMVPTC) is one of the rare types of papillary carcinoma. It has been associated with familial adenomatous polyposis, though it can also occur sporadically. The molecular pathogenesis of this tumor is incompletely understood. It appears that there can be molecular contributions from the RET/PTC translocations and from mutations in the APC gene and beta-catenin gene, which are both part of the Wnt signaling pathway. However, one of the most common mutations in papillary carcinoma, the BRAF mutation, has not been reported in this variant of papillary carcinoma.

OBJECTIVE

To investigate the BRAF mutational status in CMVPTC.

DESIGN

Four cases of CMVPTC (1 associated with familial adenomatous polyposis and the others apparently sporadic) were identified from the files of 3 large centers. Deoxyribonucleic acid was extracted and successfully amplified from each case. The polymerase chain reaction products were sequenced and evaluated for the T1799A BRAF mutation.

RESULTS

None of the 4 cases harbored the T1799A BRAF mutation (0/4). Conclusions.-The T1799A BRAF mutation does not appear to play a role in the tumorigenesis of CMVPTC.

Cribriform-morular variant of papillary thyroid carcinoma: molecular characterization of a case with neuroendocrine differentiation and aggressive behavior

We describe an especially aggressive case of cribriform-morular variant (C-MV) of papillary thyroid carcinoma (PTC) in a 42-year-old man with familial adenomatous polyposis who died with lung and brain metastases 17 months after thyroidectomy. The angioinvasive neoplasm combined a mixture of trabecular, solid, cribriform, and follicular patterns of growth with CD10+ morules. Follicles were devoid of colloid, and the nuclear features typical of PTC were present in some areas and missing in others. Tumor cells were positive for thyroid transcription factor-1 and, in 40% of the tumoral mass, also were positive for chromogranin and synaptophysin and were negative for thyroglobulin and calcitonin. Strong nuclear staining for beta-catenin was found in all tumor cells, as was positivity for p53 and cyclin D1. In addition to the germline heterozygous APC Ex 2-3 duplication mutation, a somatic homozygous silent p. Thr1493Thr gene variant was found in the neoplastic cells along with RET/PTC rearrangement. This tumor represents the first case of C-MV of PTC showing neuroendocrine differentiation.

Follicular thyroid carcinoma with an unusual glomeruloid pattern of growth

We describe an uncommon thyroid tumor in a 56-year-old woman. The widely infiltrating, angioinvasive neoplasm, 5 cm in diameter, exhibited a peculiar architectural growth pattern characterized by follicles with round to oval epithelial tufts growing within, often supported by a fibrovascular core mimicking the renal glomerulus. Colloid-empty follicles, tubular or elongated, were lined by pseudostratified tall, columnar cells with clear cytoplasm. Nuclei were round to oval, with evenly distributed, slightly coarse chromatin. Tumor cells were positive for thyroid transcription factor-1, thyroperoxidase, thyroglobulin, cytokeratin 18, Hector Battifora mesothelial cell, and vimentin. Scattered cells positive for S100, Wilms tumor 1 (WT1), and cytokeratins AE1/AE3 were found, with no reaction detected for cytokeratins 34betaE12, 5/6, 7, 19, or 20. There were PAX8-PPARgamma rearrangement and N-RAS mutation. No mutations were found for APC or BRAF genes, nor were RET/PTC rearrangements detected. Because of the distinctive histologic features, we propose naming this tumor follicular thyroid carcinoma with an unusual glomeruloid pattern of growth.

Unusual tumors of the thyroid gland

Thyroid neoplasms are classified into three major categories: epithelial, nonepithelial, and secondary. Most primary epithelial tumors of thyroid are derived from follicular cells. These include follicular adenoma and carcinoma (Hürthle and non-Hürthle), and papillary carcinoma and its variants. Other primary epithelial tumors include medullary carcinoma, mixed medullary and follicular carcinomas, insular and poorly differentiated carcinoma, anaplastic carcinoma, and the least common squamous carcinoma and related tumors. The nonepithelial tumors are rare; the most common include malignant lymphoma and tumors arising from the mesenchymal elements. The secondary tumors represent metastatic tumors to the thyroid usually originating in lung, kidney, and breast. In this article, the authors review the unusual tumors of the thyroid, their morphologic features, and clinical and prognostic implications.

Application of immunohistochemistry to thyroid neoplasms

CONTEXT

Thyroid lesions with nodular architecture and follicular pattern of growth often pose difficulties in accurate diagnosis during the assessment of cytologic and histologic specimens. The diagnosis of follicular neoplasm on cytology or of follicular tumor of uncertain malignant potential on histology is likely to cause confusion among clinicians and delay effective management of these lesions. Occasionally, thyroid tumors represent unusual or metastatic lesions and their accurate diagnosis requires immunohistochemical confirmation.

OBJECTIVE

To review the literature on the applications of immunohistochemistry in the differential diagnosis of thyroid tumors.

DATA SOURCES

Relevant articles indexed in PubMed (National Library of Medicine) between 1976 and 2006.

CONCLUSIONS

Our review supports the use of ancillary techniques involving a panel of antibodies suitable for immunohistochemistry and molecular analysis in the assessment of thyroid nodules. These tools can improve diagnostic accuracy when combined with standard morphologic criteria.

Familial non-medullary thyroid carcinoma: an update

Familial thyroid cancer can arise from follicular cells (familial non-medullary thyroid carcinoma (FNMTC)) or from the calcitonin-producing C-cell (familial medullary thyroid carcinoma). This is usually a component of multiple endocrine neoplasias (MEN) IIA or IIB, or as pure familial medullary thyroid carcinoma syndrome. The genetic events in the familial C-cell-derived tumors are known and genotype-phenotype correlations are well established. In contrast, the case for a familial predisposition of non-medullary thyroid carcinoma is only now beginning to emerge. Although the majority of papillary (PTC) and follicular thyroid carcinomas (FTC) are sporadic, familial tumors account for over 5% of cases. The presence of multifocal papillary carcinoma is a common feature of FNMTC. The familial follicular cell-derived tumors or non-medullary thyroid carcinomas encompass a heterogeneous group of diseases, including diverse syndromic-associated tumors and non-syndromic tumors. Based on clinico-pathologic findings, FNMTC is divided into two groups. The first includes familial syndromes characterized by a predominance of non-thyroidal tumors, such as familial adenomatous polyposis (FAP), PTEN hamartoma tumor syndrome (PHTS), Carney complex type 1, and Werner syndrome. The second group includes familial syndromes characterized by a predominance of NMTC, such as pure familial (f) PTC with or without oxyphilia, fPTC with papillary renal cell carcinoma, and fPTC with multinodular goiter. Some characteristic morphologic findings should alert the pathologist of a possible familial cancer syndrome, which may lead to further molecular genetic evaluation.

Molecular classification and biomarker discovery in papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy, with an incidence of approximately 22,000 cases in 2004 in the USA. Incidence is increasing, with a global estimate of half a million new cases this year. PTC is found in a variety of morphologic variants, usually grows slowly and is clinically indolent, although rare, aggressive forms with local invasion or distant metastases can occur. In recent years, thyroid cancer has been at the forefront of molecular pathology as a result of the consequences of the Chernobyl disaster and the recognition of the role of Ret/PTC rearrangements in PTC. Nonetheless, the molecular pathogenesis of this disease remains poorly characterized. In the clinical setting, benign thyroid nodules are far more frequent, and distinguishing between them and malignant nodules is a common diagnostic problem. It is estimated that 5-10% of people will develop a clinically significant thyroid nodule during their lifetime. Although the introduction of fine-needle aspiration has made PTC identification more reliable, clinicians often have to make decisions regarding patient care on the basis of equivocal information. Thus, the existing diagnostic tools available to distinguish benign from malignant neoplasms are not always reliable. This article will critically evaluate recently described putative biomarkers and their potential future role for diagnostic purposes in fine-needle aspiration cytology samples. It will highlight the evolution of our understanding of the molecular biology of PTC, from a narrow focus on specific molecular lesions such as Ret/PTC rearrangements to a pan-genomic approach.

Mutational analysis of the APC gene in cribriform-morula variant of papillary thyroid carcinoma

INTRODUCTION

Familial adenomatous polyposis (FAP) is an inherited autosomal dominant syndrome caused by germline mutations in the adenomatous polyposis coli (APC) gene. Papillary thyroid cancer is one of the extracolonic manifestations of FAP. A characteristic histologic feature of this type of thyroid tumor is the cribriform-morula variant of papillary thyroid carcinoma (CMVPTC).

METHODS

To investigate roles of the APC and beta-catenin genes in the development of CMVPTC, we examined germline and somatic mutations of these genes in a female patient with CMVPTC and FAP. The patient had undergone total colectomy at the age of 19 years and total thyroidectomy at age 25 years.

RESULTS

Numerous tumors were disseminated in both lobes of the thyroid gland, and histopathologic examination revealed typical CMVPTC. DNA was extracted from peripheral blood leukocytes and 12 CMVPTC tumors, and exons 1-15 of the APC gene and exon 3 of the beta-catenin gene were examined. A germline mutation was detected in exon 13 of the APC gene, and this mutation generated a premature stop codon. Six somatic mutations (922delC, 1602delA, 1821delT, 1920delG, 2706del20, 2804insA) were found in the CMVPTC specimens. All mutations were truncating mutations in the N-terminus of the APC protein. Loss of heterozygosity was not observed in the remaining tumor tissues without somatic APC mutations. There were no mutations of the beta-catenin gene in peripheral blood leukocytes or 12 CMVPTC specimens.

CONCLUSIONS

These results suggest that APC mutations play an important role in the development of CMVPTC and occur predominantly in the 5' side of the APC gene between codons 308 and 935.

Breast tumor resembling the tall cell variant of papillary thyroid carcinoma: a case report

The breast tumor resembling the tall cell variant of papillary thyroid carcinoma is a very unusual mammary carcinoma whose histologic and predominant nuclear features mimic a papillary thyroid carcinoma. We report the case of a 64-year-old woman who presented with a palpable nodule in the right breast. Fine needle aspiration disclosed abundant cellularity with isolated cells, sheets, and papillary formations of epithelial cells with nuclear grooves. Histologically, the neoplastic cells were arranged in a solid to papillary architecture, with follicular-like and cribriform areas. The cells were columnar to cuboidal with eosinophilic cytoplasm, clear chromatin, nuclear grooves, and occasional nuclear pseudoinclusions. Tumor cells were positive for cytokeratins, alpha and beta-estrogen receptors, progesterone receptor, androgen receptor, CEA, and bcl-2. We searched for BRAF mutations with negative results. Recognizing the cytologic and histologic characteristics of these peculiar mammary tumors that mimic thyroid carcinomas can avoid unnecessary clinical investigations.

Immunohistochemical analysis of morules in colonic neoplasms: morules are morphologically and qualitatively different from squamous metaplasia

Morules develop in several neoplasms and have been considered as a type of squamous metaplasia despite the absence of keratinization and intercellular bridges. The objective of this study was to clarify the pathological significance of morules and to distinguish morules from squamous metaplasia in colonic neoplasms. Ten cases of morule-associated colonic neoplasms (4 adenocarcinomas, 1 adenoma with carcinoma in situ, and 5 adenomas), and 3 cases of squamous metaplasia in colonic adenocarcinoma were examined morphologically and immunohistochemically. Morules were well-defined structures composed of small, oval to short-spindled cells with bland nuclei, and frequently associated with intranuclear inclusions that were positive for biotin and biotin-binding enzymes (pyruvic acid carboxylase and propionyl CoA carboxylase). On immunohistochemical examination, morules characteristically showed nuclear overexpression of beta-catenin, cyclin D1 and p63, low Ki-67 labeling index (<1%), cytoplasmic overexpression of CD10, and no expression of cytokeratin 20. These molecules were useful for the differentiation of morules. Furthermore, p63 and 34betaE12 positivities in morules suggested that they have a basal/stem cell phenotype. Thus, morules were morphologically and qualitatively different from squamous metaplasia. We consider that morules in colonic neoplasms are cell clusters with a basal/stem cell phenotype, and have less proliferative and less invasive potential than other cancer cells.

High frequency of β-catenin mutations in borderline endometrioid tumours of the ovary

Some low-grade endometrioid carcinomas arise from a background of endometrioid tumours of borderline malignancy. To determine the molecular mechanisms involved in the initiation of endometrioid carcinoma, the present study investigated whether the genetic alterations reported in these tumours (mutations in PTEN, KRAS, and beta-catenin genes, and microsatellite instability) are already present in endometrioid tumours of borderline malignancy. Eight endometrioid tumours of borderline malignancy were studied. By immunohistochemistry, beta-catenin was expressed in the nuclei of all tumours, suggesting the presence of stabilizing beta-catenin mutations. By mutational analysis, five different beta-catenin mutations were found in seven of eight cases (90%), affecting codons 32, 33, and 37. In contrast, only one tumour harboured a PTEN mutation, which affected codon 130. Neither KRAS mutations nor microsatellite instability was detected. A review of the literature indicated that beta-catenin mutations are characteristic of well-differentiated endometrioid carcinomas, since they were present in nearly 60% of grade I but in less of 3% of grade III tumours. In conclusion, the present study identifies beta-catenin mutation as a nearly constant molecular alteration in borderline endometrioid tumours, whereas PTEN and KRAS mutations and microsatellite instability are very infrequent. The findings in the present study, and previously reported data, strongly suggest that beta-catenin mutation is an early event in endometrioid ovarian carcinogenesis, and that it is involved in the development of low-grade endometrioid tumours.

Clinical curiosity: Cribriform-morular variant of papillary thyroid carcinoma

BACKGROUND

There is an increasing awareness of the association of papillary thyroid carcinoma and familial adenomatous polyposis (FAP). Although the incidence is rare, most tend to occur in women. Several authors have described a distinctive histologic variant of papillary thyroid carcinoma, the cribriform-morular variant, which is associated with FAP but also may be encountered in patients with non-FAP. This diagnosis may precede the symptoms of colorectal polyposis.

METHODS

A healthy 36-year-old woman was seen with a left thyroid nodule, and a 34-year-old woman with FAP was seen with a right thyroid nodule; both masses were suspicious for papillary thyroid carcinoma. Both patients underwent total thyroidectomy.

RESULTS

Pathologic examination of both specimens revealed papillary thyroid carcinoma, cribriform-morular variant. The first patient subsequently underwent colonoscopy, which was negative for polyposis.

CONCLUSIONS

Patients diagnosed with the cribriform-morular variant of papillary thyroid cancer should be screened for the presence of FAP.

Distinct Molecular Alterations in Complex Endometrial Hyperplasia (CEH) With and Without Immature Squamous Metaplasia (Squamous Morules)

Several molecular alterations, most commonly PTEN mutations but also K-ras mutations, microsatellite instability, and beta-catenin mutations have been detected in endometrioid endometrial carcinoma (EEC). Specifically, mutations in the beta-catenin gene are seen in 15% to 20% of EECs, whereas immunohistochemical expression of beta-catenin ranges from 13% to 44%, nuclear staining being concentrated in areas of immature squamous metaplasia (squamous morules). Complex endometrial hyperplasia with atypia (CEH-A) is a well-known precursor of EEC, which can also show immature squamous metaplasia. In this study, we compared the immunohistochemical and molecular profiles of 13 CEH-A with and 11 CEH-A without squamous morules (SM) for mutations of beta-catenin, PTEN, K-ras, and microsatellite instability (MSI). In all cases of CEH-A with SM, beta-catenin immunostaining showed strong and diffuse nuclear expression in areas of SM and weak to moderate nuclear expression in the glandular component. Six different beta-catenin mutations were found in 7 of 13 cases (54%) (G34E, G34V, S33C, D32Y, S33F, D32A); however, no mutations of the PTEN or K-ras genes were identified. beta-Catenin immunostaining showed focal nuclear staining in only 2 cases of CEH-A without SM. Only 1 case had a beta-catenin mutation (S45A), which was associated with a K-ras mutation (G12D). Another 3 cases had both PTEN and K-ras mutations (C296Stop Ex 8 and G12V, 244del C Ex 7 and G12D, 251ins TGAT Ex 7 and G13D), and one had a PTEN mutation (G230E Ex 7) only. Of all 24 cases, only 1 case of CEH-A without SM showed MSI. In conclusion, marked differences in the molecular profiles regarding beta-catenin, PTEN, and K-ras mutations were observed between CEH-A with and without SM. beta-catenin mutations might represent a signaling pathway leading to a distinctive morphology in hyperplastic/neoplastic endometrium with SM. Other molecular events such as K-ras or PTEN mutations are likely to occur in CEH-A independently from beta-catenin. Furthermore, morphologic differences between CEH-A with SM and CEH-A without SM seem to correlate, at least to some extent, with the clinical course of the disease. In our series, cases of CEH-A with SM and beta-catenin alterations appeared to have a less aggressive behavior when compared with CEH-A without SM and with K-ras and PTEN mutations.

Hereditary hormone excess: genes, molecular pathways, and syndromes

Hereditary origin of a tumor helps toward early discovery of its mutated gene; for example, it supports the compilation of a DNA panel from index cases to identify that gene by finding mutations in it. The gene for a hereditary tumor may contribute also to common tumors. For some syndromes, such as hereditary paraganglioma, several genes can cause a similar syndrome. For other syndromes, such as multiple endocrine neoplasia 2, one gene supports variants of a syndrome. Onset usually begins earlier and in more locations with hereditary than sporadic tumors. Mono- or oligoclonal ("clonal") tumor usually implies a postnatal delay, albeit less delay than for sporadic tumor, to onset and potential for cancer. Hormone excess from a polyclonal tissue shows onset at birth and no benefit from subtotal ablation of the secreting organ. Genes can cause neoplasms through stepwise loss of function, gain of function, or combinations of these. Polyclonal hormonal excess reflects abnormal gene dosage or effect, such as activation or haploinsufficiency. Polyclonal hyperplasia can cause the main endpoint of clinical expression in some syndromes or can be a precursor to clonal progression in others. Gene discovery is usually the first step toward clarifying the molecule and pathway mutated in a syndrome. Most mutated pathways in hormone excess states are only partly understood. The bases for tissue specificity of hormone excess syndromes are usually uncertain. In a few syndromes, tissue selectivity arises from mutation in the open reading frame of a regulatory gene (CASR, TSHR) with selective expression driven by its promoter. Polyclonal excess of a hormone is usually from a defect in the sensor system for an extracellular ligand (e.g., calcium, glucose, TSH). The final connections of any of these polyclonal or clonal pathways to hormone secretion have not been identified. In many cases, monoclonal proliferation causes hormone excess, probably as a secondary consequence of accumulation of cells with coincidental hormone-secretory ability.

Cyclooxygenase-2 in normal, hyperplastic and neoplastic follicular cells of the human thyroid gland

This study was undertaken to investigate cyclooxygenase-2 (COX-2) expression in follicular cells of the human thyroid. COX-2 expression was studied immunohistochemically in a total of 174 samples. COX-2 immunoreactivity was confined to the cell cytoplasm with the nuclei remaining unlabelled. COX-2 expression was observed in five cases (17.2%) of normal follicular cells and in one case (16.6%) of solid cell nests. Follicular carcinoma expressed COX-2 more frequently than follicular adenoma (93.4% vs 21.1%) (p<or=0.001). A higher percentage of cases of papillary microcarcinomas up-regulated COX-2 in comparison with all papillary carcinomas (p<or=0.05). However, we could not establish any relationships among COX-2, patients' ages or lymph node metastases in papillary carcinomas. COX-2 expression was found in 12 (92.3%) poorly differentiated carcinomas and in 13 (92.8%) undifferentiated carcinomas. We found that COX-2 is not always useful as a marker of malignancy. Our results suggest that COX-2 plays a role in progression of all thyroid carcinomas, but in papillary carcinomas, seems more important only in the early stages. COX-2 expression in the undifferentiated carcinoma deserves special consideration due to its prognosis and to the fact that selective COX-2 inhibitors were found to enhance tumour response to radiation in some studies.

Multiple signaling pathways converge on beta-catenin in thyroid cancer

The beta-catenin pathway has been conclusively demonstrated to regulate differentiation and patterning in multiple model systems. In thyroid cancer, alterations are often seen in proteins that regulate beta-catenin, including those of the RAS, PI3K/AKT, and peroxisome proliferation activated receptor-gamma (PPARgamma) pathways, and evidence from the literature suggests that beta-catenin may play a direct role in the dedifferentiation commonly observed in late-stage disease. RET/PTC rearrangements are frequent in thyroid cancer and appear to be exclusive from mutational events in RAS and BRAF. Activation of AKT by phosphatidylinositide-3 kinase (PI3K), a RAS effector, results in GSK3beta phosphorylation and deactivation and subsequent beta-catenin upregulation in thyroid cancer. Activating mutations in beta-catenin, which have been demonstrated in late-stage thyroid tumors, correlate with beta-catenin nuclear localization and poor prognosis. We hypothesize that activation of the RAS, PI3K/AKT, and PPARgamma pathways ultimately impinges upon beta-catenin. We further propose that if mutations in BRAF, RAS, and RET/PTC rearrangements are mutually exclusive in certain thyroid tumors or tumor types, as has already been shown for papillary thyroid cancer, then these interconnected pathways may cooperate in the initiation and promotion of the disease. We believe that clinical benefit for thyroid cancer patients could be derived from disrupting the middle or distal pathway effectors of these pathways, such as AKT or beta-catenin.

Cribriform-morular variant of papillary thyroid carcinoma: clue to early detection of familial adenomatous polyposis-associated colon cancer

The cribriform-morular variant (CMV) of papillary thyroid carcinoma (PTC) is a rare histologic subtype of PTC that shows a combination of growth patterns including cribriform and spindle cell areas. The thyroid cancer with this unique histology was originally reported in patients with familial adenomatous polyposis (FAP), although it was later found in patients without polyposis as well. Because of its rarity, its clinical features are not clear. We reviewed seven patients with CMV-PTC who were found among 4194 patients with PTC in our pathology files between June 1991 and March 2003. The prevalence of CMV was 0.16% among all PTCs. We invited these patients to our hospital so we could obtain a detailed family history and recommend colonoscopic examination and germline APC gene analysis. Two patients without subjective symptoms had polyposis of the colon and colon cancers. Germline APC gene mutations were found in both patients. The father of a patient who refused the invitation was revealed to have undergone surgery for colon polyposis. In the remaining four patients, neither polyposis nor APC gene mutation was found. Common clinical features included a young age (mean 25 years), predominance of females, circumscribed tumors, negative node metastasis, and no recurrence of the thyroid cancer after surgery. Two of the three patients with colon polyposis had bilateral multiple thyroid tumors, whereas the remaining four (without polyposis) had a solitary tumor. The histopathology of CMV in patients with PTC should arouse a suspicion of FAP, especially if there are multiple tumors. This finding can lead to early detection of colon cancer.

Pulmonary sclerosing hemangioma associated with familial adenomatous polyposis

A 45-year-old woman presented with asymptomatic solid tumor in the lower right lobe of the lung. Histologically, the tumor comprised a monolayer of surface cells and round stromal cells displaying sclerotic areas. Immunohistochemical studies suggested a diagnosis of sclerosing hemangioma. Interestingly, morular lesions were also observed. Analyses of the gastrointestinal (GI) tract showed mild familial adenomatous polyposis (FAP) and numerous fundal gland polyps, indicating attenuated FAP (AFAP). All components of the sclerosing hemangioma displayed aberrant nuclear and cytoplasmic expression of beta-catenin. However, such findings were much weaker in adenomas of the GI tract and were barely observed in fundal gland polyps. These results strongly suggest an association between sclerosing hemangioma and the AFAP. To the best of our knowledge, this is only the second report of lung tumor associated with FAP and is the first describing an association with sclerosing hemangioma. A new category of FAP-associated lung tumors may be indicated.

Papillary thyroid carcinoma associated with familial adenomatous polyposis: molecular analysis of pathogenesis in a family and review of the literature

We found a case of a papillary thyroid carcinoma that was accompanied by a familial adenomatous polyposis (FAP) in a 29-year-old female. She had hundreds of adenomas inside the entire colon and a congenital hypertrophy of the retinal pigmented epithelium (CHRPE). The patient underwent a total thyroidectomy and a central compartment neck node dissection. Gross examination of the thyroid identified two solid and cystic lesions. The pathological finding of thyroid cancer revealed a mixture of a peculiar nuclear clearing, cribriform, morula formation, trabecular and papillary pattern. The patient's brother had undergone a total colectomy due to FAP at the age of 25. Genetic analyses of the patient's family members revealed that she and her brother had the same germline mutation, in which five nucleotides (AAAGA) were deleted from codon 1309 of the adenomatous polyposis coli (APC) gene exon 15. Strong and frequent immunoreactivities of beta-catenin and p53 were evident in the tumor tissue. At the time of writing, a preventive colectomy was still under consideration for the patient. Genetic counseling was given to the other family members, who were not attacked by this disease, in order to allay their fears of cancer.

Morules in cribriform-morular variant of papillary thyroid carcinoma: Immunohistochemical characteristics and distinction from squamous metaplasia

Morules are a diagnostic clue to the cribriform-morular variant (C-MV) of papillary thyroid carcinoma, and are superficially similar to squamous metaplasia. In order to clarify the histogenesis of morules and differentiate them from squamous metaplasia, we immunohistochemically compared the morules in five cases of C-MV with squamous metaplasia in six cases of diffuse sclerosing variant (DSV) of papillary thyroid carcinoma. The squamous metaplastic cells were immunopositive for low- and high-molecular-weight cytokeratin, whereas the morular cells were negative or focally positive. Vimentin-positive cells were observed focally in the morules and squamous metaplasia, except for one case of CMV that showed intense positivity. The morular cells showed weak cytoplasmic positivity for beta-catenin, and the cell membrane was not highlighted. Some nuclei of the morular cells were also positive for this antibody. Beta-catenin was intensively positive along the cell membrane of the metaplastic cells, and did not react against the nuclei or cytoplasm. Bcl-2 was positive in the morular cells, but negative in the metaplastic cells. S-100 protein-positive dendritic cells were observed in the metaplastic nests, but not in the morules. We argue that morules appear in connection with nuclear and cytoplasmic aberrant localization of beta-catenin, and are not an early form of squamous metaplasia.

Cribriform-Morular Variant of Papillary Carcinoma: Association with Familial Adenomatous Polyposis - Report of Three Cases and Review of Literature

We describe a rare variant of papillary thyroid carcinoma (PTC), the Cribriform-Morular Variant (C-MV). A handful of cases have been described in the literature of this entity. They exhibit the morphologic features of a distinctive papillary neoplasm along with solid, cribriform, and squamoid-morular areas. The cribriform and morular features make this a separate entity which could be mistaken for a high grade aggressive thyroid neoplasm. These lesions are usually associated with familial adenomatosis polyposis (FAP) but rarely may be sporadic. We report three cases that we have encountered.