Immunohistochemical detection of XIAP and p63 in adenomatous hyperplasia, atypical adenomatous hyperplasia, bronchioloalveolar carcinoma and well-differentiated adenocarcinoma.

The critical distinction of bronchioloalveolar carcinoma (BAC), well-differentiated adenocarcinoma (WDAC) of lung, adenomatous hyperplasia (AH) and atypical adenomatous hyperplasia (AAH), is based on morphological criteria alone, and is therefore potentially subjective. We examined expression of two markers, X-linked inhibitor of apoptosis protein (XIAP), the most potent of the inhibitor of apoptosis protein (IAP) family, and p63, a marker of bronchial reserve cells (BRC) and squamous cells, in these entities. H&E slides of 37 tissue blocks from 27 patients were reviewed and classified as AH (n=7), AAH (n=8), BAC (n=9) and WDAC (n=13). Immunostaining was performed on 4 mum sections with monoclonal anti-XIAP and monoclonal anti-p63. Granular or heterogeneous cytoplasmic staining for XIAP and nuclear staining for p63 were considered positive. Neither XIAP nor p63 were detected in normal lung alveolar cells. All seven AHs were negative for XIAP and negative or focally positive for p63. All eight AAHs were positive for XIAP and displayed p63 positivity in scattered cells. All BACs displayed XIAP positivity, which ranged from focal/weak to diffuse/strong. p63 was negative in seven and focally positive in two of nine BACs. Twelve of 13 WDACs showed XIAP positivity in a similar pattern to BAC; all were negative for p63. One aberrant case diagnosed on H & E as WDAC was negative for XIAP but strongly positive for p63. Significant XIAP expression appears to be useful for distinguishing AAH from AH. Commonality of XIAP staining in AAH, BAC and WDAC supports the possibility that AAH may be a pre-malignant lesion. The rarity of p63 expression confirms previous reports and supports a nonbronchial histogenesis of these entities. In contrast, diffuse p63 staining may facilitate the identification of rare cases that may have been misclassified as alveolar in origin based on morphology but may be of BRC origin.     

Unique Cellular Features in Atypical Adenomatous Hyperplasia of the Lung: Ultrastructural Evidence of Its Cytodifferentiation

Atypical adenomatous hyperplasia (AAH) of the lung could be a good material to understand the histogenesis of peripherally occurring, well-differentiated adenocarcinoma. However, its true biological significance remains to be clarified. The authors present the histomorphological studies of this lesion and compare the ultrastructure with that of nonmucinous bronchioloalveolar carcinoma (BAC) to define characteristic features of AAH. Light microscopy showed the well-preserved pulmonary architecture, proliferated neoplastic cells without marked cellular atypia, and no transitional area to obvious adenocarcinoma. Intranuclear inclusion was present in a large number of neoplastic cells. Electron microscopy revealed that cuboidal or low columnar neoplastic cells proliferated actively but were not crowded on slightly thickened fibrous alveolar septa with both Clara-like granules and small lamellar bodies in the cytoplasm resembling that of Clara cell and type 2 pneumocyte. Some of the nuclei had characteristic invaginations of its nuclear membrane. Although the findings appear to be nonspecific for AAH, the authors emphasize that AAH is an alveolar intraepithelial neoplasia that represents a very early stage in the continuous developmental spectrum of adenomatous neoplasia in the bronchioloalveolar region corresponding to dysplasia or intraepithelial neoplasia in other organs, and will give the significance to speculate its histogenesis.     

P63 in pulmonary epithelium,pulmonary squamous neoplasms,and other pulmonary tumors

p63 is a p53-homologous nuclear protein that appears to play a crucial role in regulation of stem cell commitment in squamous and other epithelia. In this study, p63 expression was examined in benign lung and in neoplasms of pulmonary origin. Eighty sections from routinely fixed and processed archival bronchoscopic biopsy or lobectomy specimens were pretreated with citric acid (pH 6.0) for antigen retrieval, then incubated overnight with anti-p63 monoclonal antibody 4A4. Slides were stained using a streptavidin-biotin kit and diaminobenzidine as chromagen, and were counterstained with hematoxylin. In normal lung, p63 intensely stained nuclei of bronchial reserve cells but did not stain ciliated cells, alveolar epithelial cells, or nonepithelial cells. The lower strata of squamous metaplastic bronchial epithelium stained positively. All squamous-cell carcinomas stained positively (n = 30). In some well-differentiated carcinomas, staining was found at the periphery of tumor nests but was negative in central zones showing squamous maturation. Poorly differentiated carcinomas showed very high proportions (80% to 100%) of p63-positive nuclei. All small-cell carcinomas were p63 negative (n = 9). Staining of bronchioloalveolar carcinomas (n = 7) and adenocarcinomas (n = 23) was variable: some tumors showed no detectable staining, others showed heterogeneously positive staining. Adenosquamous carcinomas (n = 5) displayed a unique basalar staining pattern. Carcinoid tumors were almost entirely negative (n = 5). We conclude that p63 is expressed in benign bronchial stem cells, in neoplastic cells with either squamous differentiation or squamous differentiating potential, and in a subpopulation of adenocarcinomas. p63 immunostaining may also aid in some histopathologic distinctions, such as in small biopsies where the differential diagnosis is poorly differentiated squamous carcinoma versus small-cell carcinoma. A stem cell biology-based classification system for squamous carcinomas is proposed.     

Unique Cellular Features in Atypical Adenomatous Hyperplasia of the Lung: Ultrastructural Evidence of Its Cytodifferentiation

Atypical adenomatous hyperplasia (AAH) of the lung could be a good material to understand the histogenesis of peripherally occurring, well-differentiated adenocarcinoma. However, its true biological significance remains to be clarified. The authors present the histomorphological studies of this lesion and compare the ultrastructure with that of nonmucinous bronchioloalveolar carcinoma (BAC) to define characteristic features of AAH. Light microscopy showed the well-preserved pulmonary architecture, proliferated neoplastic cells without marked cellular atypia, and no transitional area to obvious adenocarcinoma. Intranuclear inclusion was present in a large number of neoplastic cells. Electron microscopy revealed that cuboidal or low columnar neoplastic cells proliferated actively but were not crowded on slightly thickened fibrous alveolar septa with both Clara-like granules and small lamellar bodies in the cytoplasm resembling that of Clara cell and type 2 pneumocyte. Some of the nuclei had characteristic invaginations of its nuclear membrane. Although the findings appear to be nonspecific for AAH, the authors emphasize that AAH is an alveolar intraepithelial neoplasia that represents a very early stage in the continuous developmental spectrum of adenomatous neoplasia in the bronchioloalveolar region corresponding to dysplasia or intraepithelial neoplasia in other organs, and will give the significance to speculate its histogenesis.     

Analysis of p21Waf1/Cip1 expression in normal, premalignant, and malignant cells during the development of human lung adenocarcinoma.

Our studies suggested that adenocarcinoma of the peripheral lung mostly develops by several steps from atypical adenomatous hyperplasia through early adenocarcinoma to overt adenocarcinoma, and that some p53 abnormalities play an important role in this progression. In the present study, we examined by immunohistochemistry the expression of p53-inducible cyclin-dependent kinase inhibitor p21Waf1/Cip1 (p21) in the cells at various developmental stages of lung adenocarcinoma (32 lesions of adenomatous hyperplasia, 14 of early adenocarcinoma, 23 of well differentiated adenocarcinoma, and 17 of moderately or poorly differentiated adenocarcinoma) in comparison with 19 reactive proliferative lesions and analyzed the relationship between p53 and p21 expression. Bronchioalveolar cells in the normal lung expressed very little or no p21 and no p53 expression. In not only reactive but also neoplastic lesions regardless of their developmental stage, the cells expressed p21 at various frequencies. The average labeling indices ranged from 5.4 to 13.8%, and there was no significant difference between any of these categories. The expression of p21, however, tended to be relatively low in moderately and poorly differentiated adenocarcinomas (5.5%) compared to well differentiated adenocarcinomas (12.2%), and high-level p21 expressors (10% < or = positive cells) were more frequent in the latter group (1 of 17 (6%) versus 3 of 23 (35%), P < 0.05), suggesting that p21 expression is affected by the degree of differentiation of the neoplastic cells. Although the correlation was positive between the expression of p21 and p53 in reactive lesions (r = 0.88; P < 0.001), none was found in neoplastic lesions at any step or grade (-0.12 < or = r < or = 0.26). These results indicated that p21 expression depends upon p53 expression in reactive lung cells, whereas p21 expression is at least in part independent of that of p53 from the earliest to the most fully developed step of lung adenocarcinoma tumorigenesis. We concluded that disruption of the p53-dependent cell cycle regulation is a very early event in the tumorigenesis of lung adenocarcinoma.     

Clonal growth of atypical adenomatous hyperplasia of the lung: cytofluorometric analysis of nuclear DNA content

The nuclear DNA content of 13 cases of atypical adenomatous hyperplasia (AAH) associated with adenocarcinoma, eight cases of small-sized well differentiated adenocarcinoma in which the tumors were less than 2.5 cm in size with no tumor recurrence within 5 yr after surgery, and eight cases of reactive type 2 pneumocyte hyperplasia of the lung was determined by cytofluorometry. Of the AAHs, four were solitary and composed entirely of cells of AAH (Group 1), and the remaining nine were in continuity with the focus of adenocarcinoma (Group 2). The average mean nuclear DNA content of the AAHs was significantly greater than that of reactive type 2 pneumocyte hyperplasia (p less than 0.005) and significantly smaller than that of adenocarcinoma associated with AAH (p less than 0.05). However, no significant difference was found in nuclear DNA content between AAH and small-sized well differentiated adenocarcinoma. Aneuploid stem lines were found in seven of the 13 (53.8%) AAHs, ten of the 13 (76.9%) adenocarcinomas associated with AAH, and five of the eight (62.5%) small-sized well differentiated adenocarcinomas but in none of the reactive type 2 pneumocyte hyperplasias. DNA histogram patterns I and II, in which aneuploid cells were less frequently present than in patterns III and IV, were more common in AAH than in adenocarcinoma associated with AAH and small-sized well differentiated adenocarcinoma. All of the reactive type 2 pneumocyte hyperplasia showed pattern I. As to the average mean nuclear DNA content, incidence of aneuploid stem lines, and DNA histogram pattern, there was no significant difference between groups 1 and 2 of the AAHs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cytopathologic diagnosis of bronchioloalveolar carcinoma: does it correlate with the 1999 World Health Organization definition?

We identified 29 bronchial washing, bronchoalveolar lavage, sputum, and fine-needle aspiration specimens with corresponding surgical pathology specimens with features of bronchioloalveolar carcinoma (BAC). Surgical pathology correlates were reclassified according to the 1999 World Health Organization classification into pure BAC, mixed adenocarcinoma-BAC (AD-BAC), and papillary adenocarcinoma (PAP-AD). Twelve cases of invasive pulmonary adenocarcinoma (INV-AD) without a bronchioloalveolar component were reviewed for comparison. The cytology slides were evaluated for 12 features of BAC. No statistically significant feature permitted separation of BAC from AD-BAC or from PAP-AD. However, comparison of BAC with INV-AD identified 9 statistically significant cytologic features: clean background, absence of 3-dimensional clusters, neoplastic cells in flat sheets, orderly arrangement of cells with round uniform nuclei, predominance of mucinous cells, absence of nuclear overlap, absence of irregular nuclear membranes, fine granular chromatin, and nuclear grooves that were features of BAC cases. Although cytologic evaluation cannot prospectively diagnose BAC, the bronchioloalveolar pattern may be recognized and suggests in situ proliferation that is present in BAC, AD-BAC, or PAP-AD. The bronchioloalveolar pattern must be correlated with clinical, radiographic, and histologic parameters to determine whether the tumor is localized, multifocal, or diffuse and whether there is parenchymal invasion.     

Characterization of adenocarcinoma of the lung in a familial adenomatous polyposis patient

The incidence of several extracolonic tumors, such as duodenal carcinoma, is higher in familial adenomatous polyposis (FAP) patients than in the general population, but there is little information about lung carcinoma in FAP. A 43-year-old woman presented with a lung tumor 17 years after total colectomy for FAP. Pathohistological analysis of the lung tumor demonstrated mixed adenocarcinoma consisting of a papillary adenocarcinoma component and a bronchioloalveolar carcinoma component. Sequencing analysis indicated a germline APC mutation from TCA to TGA (stop) at codon 1110, but no pathogenic germline MYH mutations. The other APC allele in the lung carcinoma was not inactivated by somatic mutations, promoter methylation, or chromosomal deletion. No somatic mutations in any of the coding regions of the p53 gene or in the mutation hot spot regions of the K-ras or EGFR genes were detected in the carcinoma. Amplification, however, of three chromosome regions, 5p, 8q, and 12q14-12q21, was identified in the carcinoma on genome-wide high-resolution single-nucleotide polymorphism (SNP) microarray. The present results suggest that the chromosomal copy number alterations detected on SNP microarray were involved in the carcinogenesis of the adenocarcinoma of the lung in the present FAP patient.     

Epidermal growth factor receptor gene mutations in atypical adenomatous hyperplasias of the lung.

Activating epidermal growth factor receptor (EGFR) gene mutations are frequently detected in lung adenocarcinomas, especially adenocarcinomas with a nonmucinous bronchioloalveolar carcinoma component. EGFR-mutated lung adenocarcinomas respond well to EGFR tyrosine kinase inhibitors. We previously found that most (88%) pure nonmucinous bronchioloalveolar carcinomas (adenocarcinoma in situ) already harbor EGFR mutations, indicating that the mutations are an early genetic event in the pathogenesis. We examined 54 atypical adenomatous hyperplasias, precursor lesions of lung adenocarcinomas, obtained from 28 Japanese patients for the hotspot mutations of EGFR exons 19 and 21 and K-ras codon 12. EGFR mutations were observed in 17 of the 54 (32%) atypical adenomatous hyperplasias examined: Ten and seven atypical adenomatous hyperplasias had deletion mutations at exon 19 or point mutations (L858R) at exon 21, respectively. We did not observe apparent histological differences between atypical adenomatous hyperplasias with and without EGFR mutations. K-ras mutation (G12S) was detected in only one atypical adenomatous hyperplasia. As EGFR mutational frequency of atypical adenomatous hyperplasias was much lower than that of nonmucinous bronchioloalveolar carcinomas, we surmise that EGFR-mutated atypical adenomatous hyperplasias, but not atypical adenomatous hyperplasias with wild-type EGFR, are likely to progress to nonmucinous bronchioloalveolar carcinomas.     

Relation of fine structure to prognosis for papillary adenocarcinoma of the lung

Eight cases of papillary adenocarcinoma of the lung were investigated by light and electron microscopy. Prognoses for all but one patient were favorable. Two patients (husband and wife) who underwent tumor resection during the same year experienced no disease-related problems for more than seven years afterward. Microscopic study of the papillary adenocarcinomas revealed columnar, peg-shaped, mucus-secreting tumor cells lining the alveoli. The tumor tissue contained alveolar macrophages, with some multinucleated giant cells, interstitial lymphoid infiltrates, mildly thickened alveolar walls, and a few pneumoconiotic foci. These inflammatory stromal reactions in the tumor tissue might have been associated with the favorable prognoses. Nuclear inclusions were detected in some tumor cells in all cases. Ultrastructurally, the inclusions contained tubular, granular, crystalline, and electron-dense homogeneous structures in addition to unclassifiable nuclear bodies. The tubular structures were in close proximity to inner leaflets of the nuclear membranes. The papillary adenocarcinoma cells had features of totipotential bronchioloalveolar cells, differentiating toward type II pneumocytes, Clara cells, and ciliated epithelial cells.     

Molecular alterations in atypical adenomatous hyperplasia occurring in benign and cancer-bearing lungs.

Atypical adenomatous hyperplasia (AAH) is considered to be a precursor lesion of the lung adenocarcinoma. Several genetic abnormalities have been reported in AAH associated with adenocarcinoma, but little is known about AAH associated with benign lung lesions. To address this we compared the molecular characteristics of AAH present in benign conditions to those coexisting with carcinoma. Seven cases of AAH from resected non-neoplastic lungs (AAH-B) and 12 cases from lungs resected for primary lung carcinoma (AAH-M) were analyzed for loss of heterozygosity (LOH) using 21 polymorphic microsatellite markers situated in proximity to known tumor suppressor genes on chromosomes 3p, 5q, 7p, 9p, 10q, and 17p. Direct DNA sequencing for K-ras mutation was also performed. There was a broad range of LOH in both groups. No LOH was identified in 3 cases (25%) of AAH-M, but all cases of AAH-B showed LOH (P=0.26). Six cases (50%) of AAH-M and 3 cases (43%) of AAH-B showed loss at 1 marker (P=0.99). LOH at 2 or more markers was identified in 3 (25%) cases of AAH-M and 4 (57%) cases of AAH-B (P=0.32). LOH was most frequently detected on chromosomes 3p and 10q in both groups. The difference in overall fractional allelic loss between the 2 groups did not reach statistical significance. K-ras mutations were not identified in either group. Our results showed a significant overlap in LOH patterns between AAH with or without coexistent lung malignancy. Therefore, AAH may represent a smoking induced low-grade neoplastic lesion that may be a precursor lesion of only a subset of invasive lung adenocarcinoma.     

Proposal of an improved histological sub-typing system for lung adenocarcinoma �C significant prognostic values for stage I disease

We have established a concise sub-typing system suitable for predicting the postoperative outcome in cases of stage I lung adenocarcinoma (ADC), using morphometric profiling. The association between postoperative disease recurrence and a variety of morphological features including histological architecture, cell type, cytoplasmic color/internal structure, nuclear shape/size, chromatin pattern, and nucleoli count/remarkableness, was analyzed. Histological architecture had the most prognostic value and could be subdivided into low-grade (bronchioloalveolar, papillary and tubular: “tubular” in this paper is defined as a tubular or glandular structure lined with single-layered neoplastic cells) and high-grade (acinar and solid: “acinar” is defined as a tubular or glandular structure lined with poly-layered neoplastic cells or as a fused glandular structure such as the cribriform pattern) components. The subgroups separated based on a cut-off value, 71.5% of the high-grade component comprised by a tumor, which was calculated according to a relative operating characteristic curve, exhibited a significant difference in disease recurrence [estimated 5-year disease-free survival rate, 95.3% in the low-grade group versus 66.7% in the high-grade group, hazard ratio 7.35, Log-rank test p = 0.002]. The sub-grouping system is concise and suitable for practical use. It will improve the histological classification of ADC.     

The histological diagnosis of clinically documented cases of cryptogenic organizing pneumonia: diagnostic features in transbronchial biopsies

Eleven cases of clinically diagnosed cryptogenic organizing pneumonia were examined in order to establish the histological features found at transbronchial biopsy and to correlate this with open lung biopsy which followed in six cases. The essential pathological feature was the presence of buds of granulation tissue (Masson bodies) indicating organization of a persistent exudate by fibroblasts and capillaries within alveoli, with preservation of the alveolar architecture. In addition, both acute and chronic inflammatory cells were present in the interstitium. These features, combined with the clinical history, were sufficient for a diagnosis in seven of the 11 cases on transbronchial biopsies. Four biopsies lacked these features. Patients proceeded to open lung biopsy in addition to the two with histological features of cryptogenic organizing pneumonia on transbronchial biopsy, but where the clinician wanted to eliminate other pathology because of rapid clinical deterioration. Five of the six cases coming to open lung biopsy confirmed cryptogenic organizing pneumonia with Masson bodies within alveoli, but changes were focal in three with very few Masson bodies in one. One case which had the features on transbronchial biopsy lacked them in the open lung biopsy. Transbronchial biopsy, therefore, can yield diagnostic material in the majority of patients with cryptogenic organizing pneumonia while open lung biopsy, which is considered the gold standard for interstitial lung disease, may yield negative results because of sampling error and the rapid evolution and changing pattern of the disease.     

Microglandular hyperplasia: a model for the de novo emergence and evolution of endocervical reserve cells

BACKGROUND: Microglandular hyperplasia (MGH) of the cervix in human beings is associated early with gland proliferation and terminates in mature squamous metaplasia. Using antibodies to basal cell markers, we analyzed biopsies with MGH to profile the distribution and evolution of reserve cells and their relationship to these epithelial components. DESIGN: Serial sections of 24 MGHs were subdivided into (1) early MGH with microacinar proliferation, abundant subnuclear vacuoles, and a paucity of supporting stroma and (2) late MGH with more prominent supporting stroma and/or squamous metaplasia. Serial sections were stained with antibodies to p63, bcl-2, and keratin-5. RESULTS: Three patterns of p63 staining were observed corresponding to the age of the MGH: (1) scattered staining of columnar cells, (2) focal subcolumnar staining in a reserve cell distribution, and (3) linear subcolumnar arrays of p63-positive reserve cells that in some MGHs expanded into a squamous metaplasia. Early acinar proliferations showed weak and focal columnar cell staining followed by focal subcolumnar p63-positive cells. In late lesions, p63 staining was compartmentalized to the extraglandular (or subcolumnar) areas. Stainings of p63, bcl-2, and keratin-5 were concordant. Staining for keratin 14, which localizes to squamous cells, was variable. CONCLUSIONS: The immunohistochemical profile in MGH indicates that reserve cells are created in adulthood during specialized columnar proliferations. This columnar to reserve cell transition may produce a stable population of reserve cells or a transition to squamous metaplasia. Similar patterns are seen in cervical neoplasia, suggesting a link between benign and neoplastic cervical epithelial differentiation.     

Keratin in human lung tumors. Patterns of localization of different-molecular-weight keratin proteins.

In this immunohistochemical study, antiserums to different molecular weight keratin proteins (45kd, 46kd, 55kd, and 63kd) were utilized to determine the profiles of keratin proteins present in a variety of pulmonary neoplasms. Different histologic types of lung carcinoma exhibited different patterns of keratin staining. Squamous cell carcinomas stained strongly for 45K, 46K, and 55K keratin, with staining for 63K restricted to areas or individual cells with cytoplasmic keratinization. Adenocarcinomas showed variable, generally weak staining for 45K, 46K, and 55K keratin and were uniformly negative for 63K keratin both in frozen and paraffin sections. Mesotheliomas and reactive mesothelial cells, by contrast, stained positively for 63K keratin in addition to keratins of lower molecular weights. Differences in staining for 63K keratin between mesothelioma and adenocarcinoma may have diagnostic application. Moreover, individual cytokeratins may serve as markers of tumor differentiation and provide information as to the origin of neoplastic cells.     

A pulmonary mucinous cystic tumour of borderline malignancy

We report a well-documented case of pulmonary mucinous cystic tumour of borderline malignancy involving the left lower lobe. The lesion was found incidentally by chest radiograph and CT scan with a provisional diagnosis of bronchioloalveolar carcinoma. The tumour was 4 cm in its greatest dimension, cystic and filled with gelatinous mucus. Microscopically, the neoplastic mucinous epithelium was composed of cuboidal cells with focally nuclear stratification and mild to moderate nuclear atypia. The patient has remained free from recurrence or metastases for 6 years. Pulmonary mucinous cystic tumour of borderline malignancy is a rare, recently described neoplasm, which spans a spectrum of tumours with malignant potential. The recent World Health Organization classification of lung tumours does not recognize this entity, which has a very good prognosis, and as such should be distinguished from classic pulmonary adenocarcinoma. Histological diagnosis can be difficult to distinguish from cystic bronchioloalveolar carcinoma or metastatic mucinous adenocarcinoma.     

Pulmonary preneoplasia – sequential molecular carcinogenetic events

Bronchial and bronchioloalveolar carcinogenesis is a multicentric and multistep process, leading to a sequential accumulation of molecular and genetic abnormalities, mainly due to exposure to tobacco carcinogens. Concomitantly, a series of morphological alterations of normal bronchial or bronchioloalveolar epithelium occur, resulting in preneoplastic and then neoplastic lesions. The three pulmonary preneoplastic changes recognized to date in the lung include bronchial squamous dysplasia and in situ carcinoma, preceding invasive squamous cell carcinoma and basaloid carcinoma, atypical adenomatous hyperplasia, a preneoplastic condition of bronchioloalveolar carcinoma, and diffuse idiopathic pulmonary neuroendocrine cell hyperplasia, a proposed precursor for carcinoid tumours. Although the gradual accumulation of molecular alterations has been widely investigated in bronchial carcinogenesis, with the aim of determining new biomarkers for early lung cancer detection in high-risk patients and targeted chemoprevention, lung adenocarcinoma pathogenesis has been only recently highlighted, with the recent discovery of epidermal growth factor receptor mutation pathway in non-smokers. This review focuses on the current status of molecular pathology in lung cancer and pulmonary preneoplastic conditions.     

Atypical goblet cell hyperplasia in congenital cystic adenomatoid malformation as a possible preneoplasia for pulmonary adenocarcinoma in childhood: A genetic analysis

Congenital cystic adenomatoid malformation (CCAM) of the lung is a congenital lesion that is sometimes complicated by bronchioloalveolar adenocarcinoma (BAC). In some cases foci of atypical goblet cell hyperplasia (AGCH) can be found within the cysts. It has been proposed that CCAM and AGCH predispose to the development of BAC. The present study used comparative genomic hybridization (CGH) to screen 22 cases of CCAM (epithelium, surrounding normal lung tissue, and both preneoplastic and neoplastic lesions) for chromosomal imbalances. Of these 22 cases, 10 were CCAM type 1, 10 were type 2, and 2 were type 3. Of the 10 cases of CCAM type 1, 2 were associated with AGCH, 1 was associated with atypical adenomatous hyperplasia (AAH) and associated tubular adenocarcinoma (AC), and 2 were associated with BAC (1 mucinous and 1 predominantly nonmucinous). The present study also involved immunohistochemistry for interleukin (IL)-13, IL-4 receptor-alpha (IL-4r alpha), cytokines involved in the differentiation of goblet cells, and mucin 2 protein (Muc2). Chromosomal aberrations were not detected in the epithelium or the surrounding normal lung tissue, whereas varying aberrations were found in the neoplastic lesions. The most frequent genomic imbalances observed in both AGCH and the carcinomas were gains in chromosomes 2 and 4. Interestingly, a predominance of gains was also reported in AC of nonsmokers. Chromosomal aberrations in AGCHs arising in CCAMs support their preneoplastic status. Nuclear expression of IL-13, IL-4r alpha, and Muc2 was detected in AGCH, whereas a cytoplasmic and nuclear reaction was seen in normal epithelium. This likely reflects an association with goblet cell differentiation, but it also drives proliferation in AGCH.