So-called hamartoma of the lung--a true neoplasm of fibrous connective tissue of the bronchi

Giant cystic pulmonary hamartoma-images

Hamartoma is the commonest benign tumor of the lung. They usually present as an asymptomatic solitary solid nodule of varying size, located peripherally in the lung parenchyma and picked up incidentally in a chest X-ray. Rarely, they may be intra-bronchial in location. A giant cystic variant of hamartoma is very rare, with only a few cases reported in literature so far. It may be misdiagnosed as any other cystic disease of the lung and thus get mismanaged. We herewith present the images of a patient with a giant cystic pulmonary hamartoma who presented with respiratory distress.

The Usefulness of Imaging Quantification in Discriminating Non-Calcified Pulmonary Hamartoma From Adenocarcinoma

Background

Patients with non-calcified hamartoma were more susceptible to surgery or needle biopsy for the tough discrimination from lung adenocarcinoma. Radiomics have the ability to quantify the lesion features and potentially improve disease diagnosis. Thus, this study aimed to discriminate non-calcified hamartoma from adenocarcinoma by employing imaging quantification and machine learning.

Methods

Forty-two patients with non-calcified hamartoma and 49 patients with adenocarcinoma were retrospentation; Manual lesion segmentation, feature quantification (e.g., texture features), and artificial neural network were performed consecutively. Independent t-test was used to conduct the inter-group comparisons of those imaging features. Receiver operating characteristic curve was performed to investigate the discriminating efficacy.

Results

Significantly higher contrast, cluster prominence, cluster shade, dissimilarity, energy, and entropy in non-calcified hamartoma were observed compared with lung adenocarcinoma. Texture-grey-level co-occurrence matrix showed a well discrimination between non-calcified hamartoma and adenocarcinoma as the detection sensitivity, specificity, accuracy, and the area under the curve were 87.22% ± 9.07%, 82.64% ± 8.07%, 85.11% ± 5.40%, and 0.942, respectively.

Conclusion

Quantifying imaging features is a potentially useful tool for clinical diagnosis. This study demonstrated that non-calcified hamartoma has a heterogeneous distribution of attenuations probably resulting from its complex organizations. Based on this property, imaging quantification could improve discrimination of non-calcified hamartoma from adenocarcinoma.

Mucinous Adenomyomatous Pulmonary Hamartoma: Clinicopathologic, Immunohistochemical, and Molecular Features of 6 Cases

Pulmonary hamartoma (PH) may show various combinations of mesenchymal tissues with entrapment of respiratory epithelium. An uncommon variant of PH prevalently consisting of smooth muscle with mucinous proliferation has been reported in literature under several definitions as sporadic reports. We collected a series of 6 leiomyomatous PH associated with mucinous growth from consultation files (3 cases) and multicentric revision of archival files among 128 consecutive surgically resected PH. The lesions have a prevalence for male gender (5:1) and lower lobes (5:1), with a mean age at diagnosis of 61 years. All cases were incidentally disclosed in asymptomatic patients and had an indolent behavior. At histology, 2 cases consisted uniquely of smooth muscle and 4 also showed mature adipose tissue. The mucinous proliferation consisted of a monotonous growth of columnar cells lacking p63-positive basal cells and expressing pan-CKs, MUC5A, and CK7, but negative with TTF-1, napsin, MUC1, MUC2, MUC6, CK20, and CDX2. Smooth muscle was negative with hormonal receptors. Molecular analysis using a multiplex gene panel did not reveal gene mutations, while ALK, BRAF, and ROS1 were negative. In conclusion, we describe a small series of uncommon PH with prevalent leiomyomatous mesenchymal component associated with a mucinous growth (mucinous adenomyomatous hamartoma). Despite the lack of basal cells coating mucinous proliferation and irregular architecture, the favorable outcome and lack of molecular alterations most likely lay for a benign/low-grade tumor. Pathologists should be aware of this unusual occurrence to prevent a diagnosis of overt malignancy, particularly in frozen section, small biopsy, and cytology.

Pulmonary giant chondromatous hamartoma with multifocal evolution in an infant

Hamartoma is the most common benign pulmonary tumor in adults, but is rarely described in the pediatric population. Giant chondromatous and progressive forms are even rarer. We report the novel case of a 13-month-old infant hospitalized for giant pulmonary chondromatous hamartoma discovered during a septic episode, rapidly progressive, with severe multifocal lesions, without clear response to several cytotoxic therapies. No predisposition syndrome was identified.

Hamartomas and other tumor-like malformations of the lungs and heart

Tumor-like malformative lesions are seen throughout the body, and they may be confused with true neoplasms by clinicians and pathologists alike. In the lungs, they are principally represented by hamartomas-which may contain chondroid, adipocytic, fibroblastic, and myxoid tissue, with entrapped bronchiolar epithelium-and congenital pulmonary airway malformations (CPAMs). The latter have been subdivided into 5 groups, based on their histological features, but they basically comprise proliferations of malformed bronchopulmonary tissues of different types. Type 1 lesions have a capacity for malignant transformation in a small proportion of cases. Malformative cardiac tumefactions include rhabdomyoma-like hamartomas; fibromatous hamartomas; and mesenchymal ventricular hamartomas, which contain cardiac muscle, smooth muscle, fat, vasogenic tissue, and nerves. Another intracardiac proliferation in the same general category is seen in the interatrial septum, in the region of the atrioventricular node. It comprises randomly-disposed gland-like profiles that are made up of endodermal epithelium. Originally thought to be a form of mesothelial lesion, that abnormality is now classified as an endodermal choristoma. All forms of pulmonary and cardiac malformations are only rarely symptomatic, and the necessity for surgical excision of them depends on the particular details of each case.

Peripherally located endobronchial hamartoma mimicking aspergilloma: a case report

We herein report the case of a 75-year-old man with a pulmonary hamartoma that mimicked aspergilloma on chest computed tomography (CT). A CT scan performed to assess an asymptomatic lesion detected on a screening chest radiograph showed a 1.3-cm diameter nodule with an air crescent sign in the left lower lobe. A diagnosis of aspergilloma was made and the patient treated with an antifungal agent for 1 year, following which he underwent radical surgery because of failure of the radiologic lesion to resolve. Pathologic examination of the resected specimen showed an endobronchial hamartoma within the B9 periphery. Peripherally located hamartomas can develop within the peripheral bronchi resulting in an air crescent appearance on radiological images.

Epidemiological and genetic clues for molecular mechanisms involved in uterine leiomyoma development and growth

BACKGROUND

Uterine leiomyomas (fibroids) are highly prevalent benign smooth muscle tumors of the uterus. In the USA, the lifetime risk for women developing uterine leiomyomas is estimated as up to 75%. Except for hysterectomy, most therapies or treatments often provide only partial or temporary relief and are not successful in every patient. There is a clear racial disparity in the disease; African-American women are estimated to be three times more likely to develop uterine leiomyomas and generally develop more severe symptoms. There is also familial clustering between first-degree relatives and twins, and multiple inherited syndromes in which fibroid development occurs. Leiomyomas have been described as clonal and hormonally regulated, but despite the healthcare burden imposed by the disease, the etiology of uterine leiomyomas remains largely unknown. The mechanisms involved in their growth are also essentially unknown, which has contributed to the slow progress in development of effective treatment options.

METHODS

A comprehensive PubMed search for and critical assessment of articles related to the epidemiological, biological and genetic clues for uterine leiomyoma development was performed. The individual functions of some of the best candidate genes are explained to provide more insight into their biological function and to interconnect and organize genes and pathways in one overarching figure that represents the current state of knowledge about uterine leiomyoma development and growth.

RESULTS

In this review, the widely recognized roles of estrogen and progesterone in uterine leiomyoma pathobiology on the basis of clinical and experimental data are presented. This is followed by fundamental aspects and concepts including the possible cellular origin of uterine fibroids. The central themes in the subsequent parts are cytogenetic aberrations in leiomyomas and the racial/ethnic disparities in uterine fibroid biology. Then, the attributes of various in vitro and in vivo, human syndrome, rodent xenograft, naturally mutant, and genetically modified models used to study possible molecular mechanisms of leiomyoma development and growth are described. Particular emphasis is placed on known links to fibrosis, hypertrophy, and hyperplasia and genes that are potentially important in these processes.

CONCLUSIONS

Menstrual cycle-related injury and repair and coinciding hormonal cycling appears to affect myometrial stem cells that, at a certain stage of fibroid development, often obtain cytogenetic aberrations and mutations of Mediator complex subunit 12 (MED12). Mammalian target of rapamycin (mTOR), a master regulator of proliferation, is activated in many of these tumors, possibly by mechanisms that are similar to some human fibrosis syndromes and/or by mutation of upstream tumor suppressor genes. Animal models of the disease support some of these dysregulated pathways in fibroid etiology or pathogenesis, but none are definitive. All of this suggests that there are likely several key mechanisms involved in the disease that, in addition to increasing the complexity of uterine fibroid pathobiology, offer possible approaches for patient-specific therapies. A final model that incorporates many of these reported mechanisms is presented with a discussion of their implications for leiomyoma clinical practice.

Pulmonary hamartoma resembling multiple metastases: A case report

The current study presents the case of a patient with multiple pulmonary nodules as observed by computed tomography. Furthermore, a marginal increase in fluorodeoxyglucose uptake was identified by positron emission tomography. Due to the appearance of multiple small nodules and a history of radical nephrectomy, a hypothetical diagnosis of pulmonary metastasis of a previously excised renal carcinoma was determined, which was confirmed by biopsy. Video-assisted thoracoscopic surgical resection of the nodules was proposed and pathological examination exhibited an unforeseen and rare observation.

Videothoracoscopic identification of chondromatous hamartoma of the lung

Introduction

The main disadvantage of a videothoracoscopic procedure is the lack of touch sensation. The probability of easily finding the lesion is usually estimated according to computed tomography (CT).

Aim

To find useful parameters of location of chondromatous hamartoma of the lung parenchyma in relation to its size to assess the probability of successful search via a videothoracoscopic approach only.

Material and methods

A group of 55 patients operated on for chondromatous hamartoma of the lung at the First Department of Surgery in Olomouc from January 2006 to June 2011 was analyzed. Initially, the tumor's longest diameter and its nearest distance to the pleural surface were measured on CT scans. Subsequently, the surgery began using the videothoracoscopic approach. A short thoracotomy with direct palpation followed when videothoracoscopy failed.

Results

No significant differences in age, sex and side of localization between the group with and without successful videothoracoscopic detection were found. A significant difference was found in the median size (p = 0.026) and the depth of the tumor (p < 0.0001) and in the calculated index “tumor size/depth” (p < 0.0001). Deeper analysis revealed that the parameters “depth” and “index size/depth” are considered to be good predictors but the parameter “size” is not a suitable predictor.

Conclusions

The main predictors of successful videothoracoscopic detection of lung chondromatous hamartoma are considered to be the depth of the tumor in the lung parenchyma with a cut-off value ≤ 7.5 mm and the index “size/depth” with a cut-off value ≥ 1.54; the tumor size is not considered to be a good predictor.

Chemical-shift MRI of pulmonary hamartomas: initial experience using a modified technique to assess nodule fat

OBJECTIVE

The aim of this study was to show the usefulness of chemical-shift MRI in the diagnosis of intranodular fat in seven patients with pulmonary hamartomas and indeterminate CT findings.

CONCLUSION

In the setting of chemical-shift MRI, the average nodule signal intensity index of pulmonary hamartomas was 45.3% (SD = 25.5%). The correlation between average nodule signal intensity and CT attenuation in Hounsfield units was -0.94. Chemical-shift MRI could be an important tool for the detection of fat in pulmonary hamartomas with inconclusive CT findings.

Endobronchial lipomatous hamartoma with mediastinal extension

Endobronchial hamartoma is a special form of pulmonary hamartoma. We report a histologically proven case of an endobronchial lipomatous hamartoma with extrabronchial-mediastinal extension in a 64-year-old patient, and we describe the computed tomography and magnetic resonance imaging findings. To our knowledge, this is the first reported case of an endobronchial hamartoma extending into the mediastinum.

Diagnostic efficacy and characteristic feature of MRI in pulmonary hamartoma: comparison with CT, specimen MRI, and pathology

OBJECTIVES

To determine the diagnostic efficacy of magnetic resonance imaging (MRI) in pulmonary hamartoma and observe the significant MRI features, other than fat or characteristic calcification revealed by computed tomography (CT).

METHODS

Six hamartomas were included and surgically resected, and we prospectively studied MRI in cases showing suggestive findings of hamartoma or indeterminate nodule on CT. We analyzed the tumor on CT and MRI (available enhancement study in 4) focusing on cleftlike structure in comparison with specimen MRI (n = 3) and histopathologic findings: presence, shape, and distribution of the cleftlike structure and signal intensity and enhancement of the cleftlike structure and main portion.

RESULTS

Computed tomography revealed suggestive findings of pulmonary hamartoma (fat or popcorn calcification) in only 3. All MRI revealed cleftlike structures particularly evident on T2-weighted images with same detectability as its specimen MRI: peripheral linear or curvilinear inclusions with sometimes intratumoral cleftlike space (n = 3), variable signal intensity, and frequent enhancement (3 in 4) pathologically correlated with the variable mesenchymal tissue components and amount arrayed along respiratory epithelial cells lining the cleft and richer vascularity than main portion of pulmonary hamartoma.

CONCLUSIONS

Magnetic resonance imaging study is a useful diagnostic tool, when a discrete pulmonary nodule demonstrates neither fat nor calcification on CT, for detecting the quite typical cleftlike structure in a pulmonary hamartoma and could provide diagnostic confidence.

Abundant cartilage formation of congenital pulmonary airway malformation--a case report

Congenital pulmonary airway malformation (CPAM) of the lung is an uncommon developmental anomaly. We report an unusual case of type 1 CPAM with abundant cartilage in a 5-year-old boy. On chest radiography, a left lung mass was detected incidentally, and tumor resection was performed under the impression of a benign tumor. The pathological examination of the mass revealed abundant cartilage in the walls of malformed bronchioles with partially cystic dilatation. We think that this case represents a cartilaginous variant of CPAM. The cartilaginous variant of CPAM should be differentiated pathologically from other pulmonary neoplasms containing abundant cartilage, such as chondroid hamartoma.

Hamartoma pulmonar como diagnóstico diferencial de metástase de carcinoma de mama: relato de caso

Relata-se o caso de uma paciente de 60 anos, em menopausa há 14 anos, com presença de nódulo pulmonar à radiografia de tórax diagnosticado no seguimento pós-operatório por neoplasia de mama. A paciente tinha história de mastectomia e linfadenectomia axilar ipsilateral por carcinoma ductal invasivo de mama, assim como de hormonioterapia, quimioterapia e radioterapia adjuvante. Após nodulectomia por vídeotoracoscopia, o exame de congelação mostrou tratar-se de um hamartoma pulmonar. Estudos recentes demonstram que 75% dos pacientes que se submeteram a cirurgia por nódulos pulmonares após mastectomia curativa de câncer de mama apresentaram metástases pulmonares, 11,5% apresentaram câncer primário de pulmão e 13,5% apresentaram lesões benignas, dentre as quais o hamartoma.

Recombinations of chromosomal bands 10q24, 12q14-q15, and 14q24 in two cases of pulmonary chondroid hamartoma studied by fluorescence in situ hybridization

Pulmonary chondroid hamartomas (PCH) are benign mesenchymal tumors consisting of at least two cytogenetic subgroups. These subgroups are defined by chromosomal alterations at either 12q14-q15 or 6p21. Cytogenetic analysis of short-term cultures from two PCHs revealed two different rearrangements with 12q14 -q15. One of these had a unique translocation t(12;14)(q14-15;q24) with presence of two normal chromosomes 12 and a der(14), but missing the der(12). The other showed a complex rearrangement between chromosomes 10 and 12 with two different derivatives. Our data have been confirmed with fluorescence in situ hybridization analysis. These cases represent variant forms of the standard translocations.

Epithelial and soft tissue tumors of the tracheobronchial tree

This article provides a broad overview of tumors that can involve the tracheobronchial tree. For the most part, the clinical, radiographic, and endoscopic presentation of these rare tumors does not differ significantly from the more common tumors of the lung. Appropriate classification of many tracheobronchial tumors ultimately requires complete sampling and a thorough microscopic evaluation. The introduction of ancillary diagnostic techniques such as immunohistochemistry and molecular analysis will continue to refine tumor classification.

Endobronchial hamartoma

OBJECTIVES

To describe clinical, endoscopic, radiographic, and follow-up characteristics of a series of patients in whom endobronchial hamartoma (EH) had been diagnosed.

METHODS

Retrospective study of all cases of hamartoma diagnosed by bronchial biopsy between 1974 and 1997 in a tertiary referral hospital in Madrid, Spain.

RESULTS

EH was diagnosed 47 patients during the study period. Four patients were excluded from the study because no clinical history was available. We analyzed the cases of 43 patients (37 men and 6 women), with a mean (+/- SD) age of 62 +/- 12 years. Seven patients had a concurrent lung neoplasm, and the EH was an incidental endoscopic finding. Among the other 36 patients, 31 had a new onset of respiratory symptoms, most commonly, recurrent respiratory infections in 16 patients (44%) and hemoptysis in a further 12 patients (33.4%). Chest radiograph findings were abnormal in 38 of 43 patients. At bronchoscopy, the lesions were equally distributed throughout the right and left lungs with no clear lobar predilection. Endobronchial obstruction was evident in 26 patients (72.2%) without concurrent neoplasm, 17 of whom underwent resection with a rigid bronchoscope and laser, with total resolution in 13 patients. Partial resolution was achieved in four patients, two of whom needed a second endoscopic procedure. Five patients were treated with open lung surgery. Clinical and endoscopic follow-up was performed in 23 patients at 1 to 73 months (mean, 17 months), and recurrence was found in 4 patients.

CONCLUSION

EH frequently produces respiratory complaints and radiographic abnormalities. Patients with endobronchial obstructions had satisfactory responses to endoscopic therapy.

An immunohistochemical study of the mesenchymal and epithelial components of pulmonary chondromatous hamartomas

Twenty-five cases of solitary pulmonary chondromatous hamartomas (PCH) were examined by immunohistochemistry to evaluate the mesenchymal and epithelial components. PCH composed of predominantly mature cartilage were designated as C type, those predominantly composed of fibromyxoid tissue as FM type, and those predominantly composed of adipose tissue as A type. FM type PCH revealed various amounts of cartilage in various developmental stages, adipose tissue and fibromyxoid tissue, compared with a uniform pattern of cartilage tissue in C type. The cells of transitional form between spindle cells, stellate cells and chondrocytes were present in FM type. Epithelial components in PCH were bronchial, bronchiolar and cuboidal cells, mostly at the periphery of PCH. S-100 protein consistently stained chondrocytes, stellate and spindle cells in the fibromyxoid tissue of solitary PCH. Fibroblast growth factor was immunolocalized to chondrocytes, spindle and stellate cells in the fibromyxoid tissue. The collagen type was associated with differentiation from primitive mesenchymal cells to chondrocytes (i. e. type I and III collagen appeared in fibromyxoid matrix and type II collagen in the cartilaginous matrix). Fibronectin coordinately appeared with type I and III collagens. The proliferating cell nuclear antigen labeling index of epithelial cells was comparable to those of neoplastic mesenchymal cells, but it was not significantly different between C type and FM type PCH. The primitive mesenchymal cells in the bronchial walls of the control premature neonates were also observed. This immunohistochemical study showed that the progenitor mesenchymal cells in the bronchial and bronchiolar walls may differentiate along chondrocytes, lipocytes, and smooth muscle cells in PCH and that epithelial proliferation is reactive and closely associated with neoplastic proliferation of the mesenchymal component.

Multiple chondromatous hamartomas of the lung: a case report and review of the literature with special reference to Carney syndrome

BACKGROUND

Multiple chondromatous hamartomas of the lung, which are very rare, are a feature of Carney syndrome. The relation between the two entities is not clear.

METHODS

A patient with multiple chondromatous hamartomas of the lung is described in this article. The literature was reviewed with special reference to the relation between multiple chondromatous hamartomas of the lung and Carney syndrome as well as the triad of gastric epithelioid leiomyosarcoma, functioning extra-adrenal paraganglioma, and pulmonary chondroma.

RESULTS

A total of 15 cases of multiple chondromatous hamartomas of the lung have been published worldwide. Two cases exhibited two other features of Carney syndrome, namely, gastric leiomyogenic neoplasms and extra-adrenal paragangliomas, and three other cases demonstrated only gastric leiomyomatous neoplasms. These five patients were all young females.

CONCLUSIONS

Some patients with multiple chondromatous hamartomas of the lung have a history of Carney syndrome. Patients with multiple chondromatous hamartomas require further examination of other sites, particularly the stomach and nervous system.

Surgical treatment of tracheal hamartoma

Tracheal hamartoma is a rare tumor and difficult to diagnose. A case is presented in which tracheal hamartoma was misdiagnosed and treated for four years as asthma. The tumor was curatively excised via posterolateral thoracotomy.

Pathological and radiological correlation of endobronchial neoplasms: Part I, Benign tumors

Benign endobronchial lung neoplasms are extremely rare. Most such neoplasms are of mesenchymal origin; however, neoplasms of submucosal gland origin and surface epithelial origin also occur. The symptomatology and radiographic features of these tumors are often indistinguishable from those of malignant lung tumors. However, recognition and early diagnosis of these lesions may allow for conservative treatment and excellent patient outcome. The clinicopathologic and radiological features of these pulmonary neoplasms are discussed.

Pulmonary hamartomas

OBJECTIVE

To analyze the clinical and pathologic features of biopsy-proven pulmonary hamartomas at a tertiary referral center.

DESIGN

We retrospectively reviewed institutional data on pulmonary hamartomas for a 17-year study period.

MATERIAL AND METHODS

The Mayo Clinic computerized medical records database was searched for patients who had biopsy, excision, or autopsy diagnosis of pulmonary hamartomas from 1976 through 1992. Medical records and all available histologic sections were reviewed.

RESULTS

Of the 215 patients with histologically confirmed pulmonary hamartoma, 141 were men and 74 were women (approximately a 2:1 ratio). Two hundred eight patients were asymptomatic, 54 of whom were undergoing assessment for a comorbid disease process. Only four patients had new onset of respiratory symptoms. The peak incidence of occurrence was in the seventh decade of life. The mean size of the hamartomas were 1.5 cm (range, 0.2 to 6.0); no lobe was predominantly involved. Most hamartomas were resected by simple or wedge excision. Sixty-three patients (29.3%) had a concurrent neoplasm (most commonly, lung carcinoma). Follow-up ranged from 2 to 192 months (mean, 61). Eight postoperative deaths occurred. No recurrent pulmonary hamartomas developed. In one patient, lung carcinoma developed 33 months after excision of a hamartoma. In a second patient, sputum cytologic findings were abnormal 9 years later. A third patient had biopsy-proven adenocarcinoma metastatic to bone and an indeterminate lung nodule 2 years after resection of a pulmonary hamartoma.

CONCLUSIONS

Pulmonary hamartomas are benign lung neoplasms that, in our referral population occurred most commonly in asymptomatic older men. A substantial number of our patients had concurrent neoplasms; however, many had been referred for cancer treatment. We found no evidence of either a malignant transformation or an unexplained association with other lung neoplasms.

Cytogenetic and histologic findings in 17 pulmonary chondroid hamartomas: evidence for a pathogenetic relationship with lipomas and leiomyomas

Pulmonary chondroid hamartomas (PCH) are benign tumors that contain mesenchymal and epithelial components. In this series, we identified clonal chromosome aberrations in mesenchymal cells from 10 of 17 PCH. Chromosome band 12q15 was rearranged most frequently (N = 4), and one case had a t(12;14)(q15;q24) that was identical cytogenetically to the characteristic translocation in uterine leiomyomas. Histologic review revealed diverse mesenchymal populations, including undifferentiated cells, cartilage, adipose tissue, and smooth muscle, in most of the PCH. These findings suggest that PCH result from neoplastic transformation of a primitive mesenchymal cell that differentiates along chondroid, adipose, and smooth muscle pathways.

Recombinations of chromosomal bands 6p21 and 14q24 characterise pulmonary hamartomas

Cytogenetic analysis of short-term cultures from seven pulmonary hamartomas revealed an abnormal karyotype in six of them. The most characteristic aberration was an exchange of material between 6p21 and 14q24, found in three tumours. Abnormalities of either 6p or 14q were seen in another two hamartomas. Other regions that were rearranged more than once were 12q (three times) and 17p (twice), sometimes in exchange with 6p or 14q and giving rise to complex derivative chromosomes. Only one tumour had aberrations that did not involve 6p, 12q, 14q, or 17p. These results-together with the data on three previously reported pulmonary hamartomas, two of which also had t(6;14)-show that recombinations between 6p21 and 14q24 are common, and hence probably pathogenetically important. The data support the view that these tumours are genuine neoplasms rather than developmental anomalies. The coexistence of a common 14q24 breakpoint in uterine leiomyomas and pulmonary hamartomas indicates that a gene important in the genesis of both tumours exists in this band.

Distribution of vitamin B12 R-binder in lung tumors. Implications for cell differentiation

Expression of vitamin B12 R-binder, a specific binding protein for vitamin B12, was studied immunohistochemically in normal lung tissues and 107 lung tumors of various types. In normal tissues, vitamin B12 R-binder (R-binder) expression was restricted to the mucous cells of bronchial or bronchiolar epithelium and submucosal glands as well as to nonciliated bronchiolar (Clara) cells. Among lung carcinomas, 38% of squamous cell carcinomas, 42% of adenocarcinomas and 23% of large cell carcinomas showed positive staining for R-binder whereas small cell carcinomas did not. These findings offer the possibility that a majority of the histologic types of lung carcinoma have common histogenetical characteristics with mucous or Clara cells. Of the bronchial gland tumors, R-binder could be detected in a mucoepidermoid carcinoma but not in adenoid cystic carcinomas. Epithelial components in both pulmonary blastomas and hamartomas showed a reactivity for R-binder, suggesting that these tumors contained components composed of cells with bronchiolar cell differentiation. The immunohistochemical examination of lung tumors, using anti-R-binder antibody, may have some implications in the cell differentiation of lung tumors.

Endobronchial hamartoma. Report of 7 cases

Seven cases of endobronchial hamartoma are presented. Preoperative fiberoptic bronchoscopic biopsy provided the histologic diagnosis in two cases, but was inconclusive in the others. The tumor was removed by endoscopic resection (2 cases), local resection via a bronchotomy (1), lobectomy (2) or pneumonectomy (1). These six patients are alive and well 2-5 years postoperatively. The seventh patient refused treatment.

Endobronchial hamartoma--a case report

Hamartoma is one of the most common benign lung tumors. Most of them are located in the lung parenchyme, but very rarely it can originate endobronchially. We report a case of endobronchial hamartoma in a 59 year old woman and a review of the literature.

Mesenchymoma of the lung (so called hamartoma): a review of 154 parenchymal and endobronchial cases

In a series of 154 patients (116 male and 38 female) with so called pulmonary hamartoma the peak incidence was in the sixth decade, with only three patients less than 20 years of age. Sequential radiographs showed that in 55 patients the tumour first appeared in adult life and that in 53 it progressively increased in size. The age incidence and progressive growth leads to the conclusion that the tumour is a benign neoplasm rather than a hamartoma, consisting of various connective tissues intersected by clefts lined by respiratory epithelium. The epithelial elements are regarded as entrapped non-neoplastic inclusions and the tumour as a purely mesenchymal neoplasm: the name mesenchymoma therefore seems the most appropriate. There were two recurrences after simple enucleation, 10 and 12 years later. A total of 142 tumours were parenchymal, and only 12 were endobronchial. All lobes were affected but there was a slight preponderance in the left upper lobe. Four patients had two (synchronous) mesenchymomas. There was an associated bronchial carcinoma in 11 patients, synchronous in six and metachronous in five.

Cartilaginous variant of congenital adenomatoid malformation of the lung

We report the occurrence of an unusual variant of congenital adenomatoid malformation (CAM) of the lung in a 16-year-old male. Abundant cartilage in the walls of malformed bronchioles, an extremely rare finding in CAM, distinguishes this lesion from the usual forms. We present the roentgenographic, computed tomographic, and pathologic features of this lesion as well as its embryologic implications. In addition, two similar cases are reviewed, one of which has been briefly discussed in a previous publication. Cartilaginous CAM should be distinguished from another lesion with abundant cartilage, the so-called pulmonary hamartoma.

Atypical lipomatous hamartoma of the lung

An unusual lipomatous tumour discovered accidentally in the right middle lobe of a 34-year old woman is described. The tumour was associated with an intrapulmonary typical chondromatous hamartoma in the same lobe but separate from the first lesion. The lipomatous tumour was primarily an intrapulmonary lipoma but in a few of the numerous sections made minute islands of cartilage and bone were discovered along with a few epithelial-lined clefts. These justify the diagnosis of a lipomatous hamartoma. Dispersed among the mature fat cells were a few immature cells with atypical nuclei. Cellular atypia in predominantly lipomatous hamartomas has not previously been reported. As the occurrence of atypical lipoblast-like cells might lead to an erroneous diagnosis of liposarcoma, this case is thought worthy of reporting.

Massive congenital mesenchymal malformation of the lung: a case report with ultrastructural study

An unusual congenital tumorous malformation of mesenchymal tissue caused severe respiratory distress in a premature infant. The solid mass, which replaced almost the entire left lung, was composed of interlacing fascicles of spindle cells that percolated through otherwise well-developed fetal lung tissue. The normal anatomic arrangement of bronchial components was altered, but bronchial cartilages were present. Ultrastructural study of the lesion showed mesenchymal cells with fibroblastic differentation.

Recurrent endobronchial soft tissue tumors

Two benign appearing endobronchial soft tissue lesions in two young patients (ages 33 and 26) were incompletely excised to conserve normal lung. Both tumors recurred four and seven years later. The first tumor had abundant small vessels in a myxomatous background (angiomyxoma); myofibroblasts formed the invasive component of the second tumor. To the best of our knowledge these two types of tumor have not been reported in the endobronchial location. Endobronchial lipoma, epithelial papilloma, inflammatory polyps, nodular sarcoid or amyloid and lymph nodes should be managed endoscopically. The potentially recurring and locally invasive endobronchial tumors such as granular cell myoblastoma, pleomorphic adenoma, angiomyxoma, and tumors of myofibroblast, and probably all other sessile benign tumors should be excised completely with part of the bronchial wall. The maximum preservation of normal lung usually does not conflict with this type of radical procedure.

Pulmonary hamartoma. An ultrastructural study

Three so-called pulmonary hamartomas were studied by electron microscopy. Histologically, the hamartomas included one case with mainly mature cartilage (chondroma), one with loose myxoid fibrous tissue and rare areas of mature cartilage, and one with only loose myxoid fibrous tissue. Ultrastructurally, a common feature in all three cases was the presence of stellate, undifferentiated mesenchymal cells. These cells were sparse in the chondroma, and abundant in the other two cases. Areas of transition between undifferentiated mesenchyme and cartilage were present in two cases (the chondroma and the myxoid fibrous tumor with areas of mature cartilage). Unusual stellate smooth muscle cells were present in areas of loose myxoid tissue. The epithelial components revealed continuity and morphologic identity to terminal bronchiolar and alveolar epithelium. A distinct basement membrane was always present. These observations support the concept that pulmonary hamartomas represent a histologic spectrum of benign mesenchymal neoplasms, which originate in peribronchial connective tissue and incorporate respiratory epithelium as they expand.

The origin of the pseudoglandular spaces in metastatic smooth muscle neoplasm of uterine origin. Report of a case with ultrastructure and review of previous cases studied by electron microscopy

The entity known as "leiomyomatous hamartoma," a term that has been used in reference to metastatic smooth muscle neoplasms of uterine origin (MSMNUO), is uncommon. Several articles have dealt with clinical and light microscopic aspects of this lesion. Four reports on the ultrastructure of this type of neoplasm have been published, but they have been primarily concerned with its smooth muscle component. Much controversy exists as to whether the glandular elements are part of the neoplastic process or preexisting pulmonary elements. This ultrastructural study confirms that the gland-like spaces represent entrapped alveoli and terminal respiratory bronchioles.

Multiple pulmonary (hamartomatous?) leiomyomas. Light and electron microscopic study

The light and electron microscopical features of the lung tumors in a case of multiple pulmonary leiomyomas are described. The differential diagnosis of leiomyomatous tumors of the lung is discussed. They have to be differentiated from lymphangio-leiomyomatosis of the lungs. In the literature, multiple pulmonary leiomyomas are generally considered to be metastases from low grade uterine leiomyosarcoma or to be hamartomatous lung tumors. This is suggested by the glandular structures both within the tumor and on the surface. However, our ultrastructural observations showed these epithelia to have features of granular pneumocytes (type II), in particular they contain lamellar bodies and possess microvilli on their surface. Their formation is considered to be a secondary reaction of alveolar lining cells to tumor growth. A possible origin of multiple pulmonary leiomyomas from the contractile system of the lung acini (contractile interstitial cells) is discussed.

Haemangioleiomyomatous tumour of the lung

A case of haemangioleiomyomatous tumour of the lung, occurring as a peripheral, solitary nodule in an asymptomatic 54-year-old man is presented. The tumour was well-demarcated and microscopically it was characterised by the presence of vascular spaces with endothelial, pericytic, and, predominantly, smooth muscle proliferation. Islands of cartilage and slit-like spaces lined by bronchial epithelium make this a hamartomatous lesion of a quite distinctive and unusual variety, which does not fit any of the well-recognised patterns of hamartomas previously described. The long-term prognosis after limited excision is considered to be favourable.