The spectrum of pulmonary mucinous cystic neoplasia : a clinicopathologic and immunohistochemical study of ten cases and review of literature

Pulmonary Mucinous Cystadenoma - A Rare Pathology

BACKGROUND

Pulmonary cystadenoma is a very rare benign tumor of the lung with slow growth rate and most often, asymptomatic.

CASE REPORT

We present the case of a 58-year-old patient admitted in the hospital for coughing with hemoptoic sputum. Standard thoracic radiography revealed a 4/5 cm macronodular opacity in the right inferior lobe, paracardiac. Thoracic computed tomography (CT) with contrast discovered a 3.8/4.7 cm homogenous mass in the right inferior lobe. After intraoperative assessment of the lesion a lower right lobectomy with mediastinal and local lymphadenectomy was performed.

CONCLUSION

Pulmonary mucinous cystadenoma is one of the primary pulmonary mucinous cystic neoplasia (PMCT) alongside PMCT of low malignancy and pulmonary mucinous cystadenocarcinoma (PMCAC). Because of this and because of the clinical and imagistic similarities between these main entities, establishing a preoperative diagnosis becomes very difficult. Therefore, histopathological and immunohistochemistry studies are mandatory in order to establish the correct diagnosis.

Pulmonary mucinous cystadenocarcinoma: an unusual presentation and literature review

Cystic lung disease is a group of heterogeneous pulmonary diseases resulting from hereditary/congenital disorders, systemic disorders and infectious causes among others. Pulmonary mucinous cystic neoplasia is a spectrum of neoplastic cystic diseases with abundant mucin, of which pulmonary mucinous cystadenocarcinoma (PMC) is a rare malignant subtype. We present a case of a 66-year-old man who presented with dyspnoea, cough, fatigue and weight loss. Imaging of his chest showed numerous cavitary lesions, and the diagnosis of PMC was made based on lung biopsy. He received palliative chemotherapy and died 1 year later. We present a literature review of PMC based on 26 reported cases, including our own.

Colloid Adenocarcinoma of the Lung: CT and PET/CT Findings in Seven Patients

OBJECTIVE

We aimed to assess CT and ¹⁸F-FDG PET/CT findings of colloid adenocarcinoma of the lung in seven patients.

MATERIALS AND METHODS

From 2010 to 2017, seven patients with surgically proven colloid adenocarcinoma of the lung were identified. CT (both enhanced and unenhanced) and PET/CT findings were analyzed, and the imaging features were compared with histopathologic reports. Clinical and demographic features were also analyzed.

RESULTS

In all cases except one, tumors showed low attenuation on unenhanced CT scans, ranging in attenuation from -16.5 to 20.7 HU (median, 9.2 HU). After contrast medium injection, enhancement was scant, so net enhancement ranged from 0.4 to 29.0 HU (median, 4.1 HU). All tumors had a lobulated contour. Stippled calcifications within the tumor were seen in one patient. The maximum standardized uptake value of tumors on PET/CT ranged from 1.5 to 4.5 (median, 3.5). In six of seven patients, FDG accumulation was seen in the tumor walls (n = 3, curvilinear uptake) or in both the tumor walls and tumor septa (n = 3, crisscross uptake). Six patients were alive without recurrence after a median follow-up period of 2.3 years (range, 2 months to 5 years). In one patient, who was alive at follow-up 4 years after imaging and had received adjuvant concurrent chemoradiation therapy after lobectomy, recurrent disease was detected 6 months after completion of the therapy.

CONCLUSION

On CT, pulmonary colloid adenocarcinomas present as lobulated homogeneously low-attenuation tumors. At PET, curvilinear or crisscross FDG uptake is seen within the tumor where tumor cells are lining the walls or septal structures.

A diagnostic challenge: An incidental lung nodule in a 48-year-old nonsmoker

A 43-year-old female with a medical history of renal stones, hypertension, diabetes mellitus Type 2, and depression presented to her urologist with bilateral flank pain. She complained of worsening exertional dyspnea over the last several months with recent weight gain. She also endorsed night sweats and intermittent, scant hemoptysis over the past year. She denied fever, chills, nausea, vomiting, diarrhea, constipation, hematuria, or excessive joint or muscle pain. Physical examination was unremarkable. Computed tomography scan of abdomen and pelvis demonstrated bilateral nonobstructing renal stones and a 1.8 cm × 1.7 cm nodular opacity in the right lower lobe of the lung, not present on previous scan 1 year prior. Surgical wedge resection was performed and subsequent pathologic examination demonstrated a 1.2 cm × 0.6 cm × 0.5 cm soft, gelatinous well-demarcated mass in the right lower lobe wedge specimen without gross evidence of necrosis or hemorrhage confirming colloid adenocarcinoma of the lung.

Mucinous cystadenocarcinoma arising from mucinous cystadenoma of the lung: case report and review of the literature

Mucinous cystadenoma is a benign tumor commonly found in the pancreas, the ovaries or the appendix. Only very few cases of these tumors originating from the lungs have been reported worldwide, with even less cases describing malignant transformation. We present the case of a 58-year-old woman with a history of recurrent pulmonary infections who underwent left upper lobectomy for lung abscess and was initially diagnosed with pulmonary mucinous cystadenoma (PMCA). Upon thorough immunohistochemical workup, especially due to carcinoembryonic antigen (CEA) positivity, intramucinous singlet cells were eventually diagnostic for invasive carcinoma, in this case a mucinous cystadenocarcinoma arising from a PCMA. PMCA is a rare benign tumor whose potential for malignant transformation has not yet been fully understood. Due to the low number of cases further studies are needed to evaluate if there is a benefit of complete oncologic resection, provided the general condition of the patient allows it. A review of the currently available literature serves to better understand the clinical, radiological and histological features of this rare tumor.

Development of Optimized, Inhalable, Gemcitabine-Loaded Gelatin Nanocarriers for Lung Cancer

BACKGROUND

Aerosol delivery of chemotherapeutic nanocarriers represents a promising alternative for lung cancer therapy. This study optimized gemcitabine (Gem)-loaded gelatin nanocarriers (GNCs) cross-linked with genipin (Gem-GNCs) to evaluate their potential for nebulized lung cancer treatment.

METHODS

Gem-GNCs were prepared by two-step desolvation and optimized through Taguchi design and characterized for physicochemical properties. Particle size and morphology were confirmed by scanning and transmission electron microscopy. In vitro release of Gem from Gem-GNCs performed in Dulbecco's phosphate-buffered saline and simulated lung fluid was evaluated to determine release mechanisms. Particle size stability was assessed under varying pH. Differential scanning calorimetry and powder X-ray diffraction were used to determine the presence and stability of Gem-GNC components and amorphization of Gem, respectively. Gem-GNC efficacy within A549 and H460 cells was evaluated using MTT assays. Mucus rheology upon treatment with Gem-GNCs, lactose, and normal saline control was measured. Andersen cascade impaction identified the aerodynamic particle size distribution of the nebulized formulation.

RESULTS

Gem-GNCs had particle size, zeta potential, entrapment efficiency, and loading efficiency of 178 ± 7.1 nm, -18.9 mV, 92.5%, and 9.1%, respectively. The Gem and formulation excipients where molecularly dispersed and configured amorphously. Gem-GNCs were stable at pH 5.4-7.4 for 72 hours. Gem release from Gem-GNCs was governed by non-Fickian controlled release due to diffusion/erosion from a matrix-based nanocarrier. Gem-GNCs elicited a 40% reduction of the complex viscosity η*(1 Hz) of human bronchial epithelial cell mucus containing 3 wt% solids to mimic mild airway disease. The nebulized Gem-GNCs had a mass median aerodynamic diameter (MMAD) of 2.0 ± 0.16 μm, geometric standard deviation (GSD) of 2.7 ± 0.16, and fine particle fraction (FPF) of 75.2% ± 2.4%. The Gem-GNC formulation did not outperform the Gem solution in A549 cells. However, in H460, Gem-GNCs outperformed the Gem IC50 reduction by ∼5-fold at 48 and 10-fold 72 hours.

CONCLUSION

Stable, effective, and sustained-release Gem-GNCs were developed. The nebulized Gem-GNCs had satisfactory MMAD, GSD, and FPF and the formulation reduced the dynamic complex viscosity of mucus consistent with increased mobility of nanoparticles.

18F-FDG PET/CT Imaging of Pulmonary Mucinous Cystadenocarcinoma with Signet Ring Cells

A 63-year-old male with a recently diagnosed right lung lesion was referred for staging. F-FDG PET/CT scan revealed a hypodense, cystic-like mass in the right upper lung lobe, which demonstrated low, diffuse ¹⁸F-FDG uptake, likely due to the presence of mucus, as well as intensely hypermetabolic right hilar and right paratracheal lymph nodes. Transbronchial biopsy revealed a primary pulmonary mucinous cystadenocarcinoma with the presence of signet ring cell carcinoma, a co-existence of two rare variants of lung adenocarcinoma. This case report demonstrates the metabolic phenotype along with the radiographic characteristics of this rare tumor and its metastases.

An update on clinicopathological, immunohistochemical, and molecular profiles of colloid carcinoma of the lung

Colloid carcinoma is a rare subtype of lung adenocarcinoma characterized by abundant pools of extracellular mucin and scant malignant epithelium. Because of the rarity of these tumors, many of the reported clinicopathological and immunohistochemical characteristics are contradictory. Moreover, the molecular alterations that underlie these tumors are unknown. We present the clinicopathological, immunohistochemical, and molecular features of 13 cases of colloid carcinoma of the lung. The patients were 9 women and 4 men between the ages of 48 and 86 years. Surgical resection and staging were performed in all patients. Seven patients were in stage T1N0M0, 3 in T2N0M0, 2 in T2N1M0, and 1 in T2N0M1. The tumor was 100% mucinous in 9 patients, whereas in 4 cases, the lesions consisted of 50% to 90% mucin pools with the remainder being a noncolloid adenocarcinoma component ranging in morphology from bronchioalveolar to acinar, papillary, solid, or mixed patterns. Follow-up ranged from 35 to 128 months. Three patients died, 1 of disease and 2 of unrelated causes. The remaining 10 patients are alive at the time of reporting, 3 with recurrent disease. Immunohistochemical studies showed CK7, CK20, and CDX2 expression in all tumors, whereas TTF-1, surfactant A, and napsin A were not present or were only focally positive in most cases. Analysis showed KRAS mutations in 2 cases. All tumors were negative for ALK gene rearrangement and EGFR mutation. Our study highlights the clinicopathological, immunohistochemical, and molecular features of lung colloid adenocarcinoma and attempts to clarify some misconceptions regarding this rare tumor.

Intra-Alveolar Intestinal Epithelium: A Reappraisal of the So-Called Mucinous Goblet-Cell Rich Carcinoma Apropos of Two Cases With Prolonged Follow-up and Literature Review

Primary pulmonary mucin-rich lesions with abundant goblet cells growing within alveolar spaces are either classified as mucinous adenocarcinoma (previously called mucinous bronchioloalveolar carcinoma) or colloid carcinoma. Some of these lesions display a morphologic pattern characterized by paucicellular discontinuous patches of nonatypical colonic type epithelium attached to alveolar walls without evidence of invasion. Immunohistochemically, these epithelial patches express an intestinal immunophenotype (CD20+, CDX-2+, CK7-, TTF-1-). None of the lesions so far reported with these histological and immunohistochemical characteristics have recurred or metastasized. Herein we describe 2 patients with this type of intra-alveolar mucinous lesions who have been meticulously followed-up for 9 and 14 years, respectively, without evidence of disease progression. Based on their histologic appearance, immunoreactivity, and on the presence of occasional CDX-2 expressing cells in terminal airways adjacent to the lesions, we propose alternative interpretations of the mucin-producing epithelium. More important, a separate provisional category for these lesions is suggested that eliminates their force inclusion as adenocarcinomas.

A rare case of mucinous cystadenoma of the lung mimicking malignancy at 18F-FDG PET/CT

We describe a rare case of pulmonary mucinous cystadenoma (PMCA) detected F-FDG PET/CT and mimicking a malignancy. A 60-year-old female patient underwent F-FDG PET/CT for metabolic characterization of a left pulmonary nodule which showed increased F-FDG uptake (SUVmax = 3.7). Based on this PET/CT finding, the patient underwent a cuneiform resection of the left pulmonary nodule. Histology demonstrated the presence of a PMCA. In our case, F-FDG PET/CT has been useful in detecting this rare pulmonary tumor.

Pulmonary mucinous cystadenocarcinoma presenting as a pleural mesothelioma

INTRODUCTION

Primary Pulmonary Mucinous Cystadenocarcinoma PPMC is an extremely rare subtype of pulmonary adenocarcinoma, with only a few dozen cases reported in the literature to date.

PRESENTATION OF CASE

We report a extremely rare case of pulmonary mucinous cystadenocarcinoma presenting as a pleural mesothelioma. 53-year-old man exposed to asbestos, he is admitted in hospital with a 5 cm mass in right pleura. He was treated by wedge resection. Sparse groups of malignant cells were microscopically observed in pools of mucin. The postoperative histopathological findings were in accordance with the diagnosis of pulmonary mucinous cystadenocarcinoma on cystic adenoid malformation of lung. 5 years later, the patient has no recurrence.

DISCUSSION

PPMC is usually asymptomatic; hemoptysis is seen occasionally. Preoperative diagnosis is very difficult to establish. Both FNA cytology and transbronchial lung biopsy seem inadequate. Our patient went on to undergo open lung biopsy and histopathological testing that confirmed the diagnosis of PMC.

CONCLUSION

It is important to differentiate this rare pathological feature of the lung from other lung tumors as the treatment is surgical rather than medical. Thoracic surgeons should bear in mind this rare tumor for the differential diagnosis of a pleural mesothelioma because this tumor has a favorable prognosis.

Mucinous cystadenoma in the lung of a captive-born moustached tamarin (Saguinus mystax)

A 2-year-old, captive-born, male moustached tamarin was subjected to necropsy examination after a fatal head trauma. A solitary, circumscribed, subpleural mass (0.6 cm diameter) was found in the right caudal lung lobe. The mass was diagnosed as a mucinous cystadenoma. Histochemical and immunohistochemical tests were performed to further characterize the tumour. Surfactant proteins A, B, C and D were not found in the neoplastic cells, suggesting that the tumour arose from a non-surfactant-producing alveolar lining cell. Pulmonary mucinous cystadenomas are uncommon benign tumours in man and have not been reported previously in animals.

Diagnosis of lung adenocarcinoma in resected specimens: implications of the 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification

A new lung adenocarcinoma classification has been published by the International Association for the Study of Lung Cancer, the American Thoracic Society, and the European Respiratory Society. This new classification is needed to provide uniform terminology and diagnostic criteria, most especially for bronchioloalveolar carcinoma. It was developed by an international core panel of experts representing all 3 societies with oncologists/pulmonologists, pathologists, radiologists, molecular biologists, and thoracic surgeons.This summary focuses on the aspects of this classification that address resection specimens. The terms bronchioloalveolar carcinoma and mixed subtype adenocarcinoma are no longer used. For resection specimens, new concepts are introduced, such as adenocarcinoma in situ and minimally invasive adenocarcinoma for small solitary adenocarcinomas with either pure lepidic growth (adenocarcinoma in situ) and predominant lepidic growth with invasion of 5 mm or less (minimally invasive adenocarcinoma), to define the condition of patients who will have 100% or near 100% disease-specific survival, respectively, if they undergo complete lesion resection. Adenocarcinoma in situ and minimally invasive adenocarcinoma are usually nonmucinous, but rarely may be mucinous. Invasive adenocarcinomas are now classified by predominant pattern after using comprehensive histologic subtyping with lepidic (formerly most mixed subtype tumors with nonmucinous bronchioloalveolar carcinoma), acinar, papillary, and solid patterns; micropapillary is added as a new histologic subtype. Variants include invasive mucinous adenocarcinoma (formerly mucinous bronchioloalveolar carcinoma), colloid, fetal, and enteric adenocarcinoma.It is possible that this classification may impact the next revision of the TNM staging classification, with adjustment of the size T factor according to only the invasive component pathologically in adenocarcinomas with lepidic areas.

Pulmonary mucinous cystadenocarcinoma: report a case and review of CT findings

A pulmonary mucinous cystadenocarcinoma is an extremely rare tumor that is considered to be a cystic variant of mucin-producing lung adenocarcinoma. We present a case of pulmonary mucinous cystadenocarcinoma in a 54-year-old woman. Chest CT scans showed a 4.3-cm-sized, lobulated, well-defined, and homogeneous mass in the right middle lobe with peripheral stippled calcifications that demonstrated low-attenuation with no enhancement after contrast administration; ¹⁸F-fluorodeoxyglucose (FDG) PET/CT demonstrated mild heterogeneous FDG uptake. The mass was diagnosed as adenocarcinoma with mucin production by transbronchial lung biopsy. Right middle lobectomy was performed, and the pathologic examination disclosed a pulmonary mucinous cystadenocarcinoma.

Cystic mucinous adenocarcinoma of the lung: a case report

Mucinous cystic tumors of the lung are uncommon, the preoperative pathologic diagnosis is difficult and their biological behavior is still controversial. We report the case of a patient with a clinically benign cystic lesion that post-operatively showed to be consistent with an invasive adenocarcinoma arising in a mucinous cystadenoma of the lung. We underline the difficulty of the clinical pre-operative diagnosis of this cystic neoplasia radiologically mimicking a hydatid cyst, and we report the negative TTF1 immunostaining potentially misleading in the differential diagnosis with metastatic mucinous carcinomas. Finallly, we evidence the presence of a pre-existing mucinous benign lesion suggesting early and complete resection of benign appearing lung cysts because they can undergo malignant transformation if left untreated or they can already harbor foci of invasive carcinoma at the time of the presentation. Even if a good prognosis, better than in other lung carcinomas, with no recurrrence or metastasis after complete surgical exicision, has been reported for cystic mucinous cystoadenocarcinomas, the follow-up showed an aggressive biological behaviour, with the early onset of metastasis, in keeping with P53 positive immunostaining and high Ki-67 proliferation index.

The "drunken honeycomb" feature of pulmonary mucinous adenocarcinoma: a diagnostic pitfall of bronchial brushing cytology

Pulmonary mucinous adenocarcinoma (PMA) is the terminology recently proposed in the new International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society (IASLC/ATS/ERS) International Multidisciplinary Classification of Lung Adenocarcinoma Guidelines for most tumors previously classified as mucinous bronchioloalveolar carcinomas (mBACs). PMA is histologically characterized by lepidic growth and at least some degree of invasive growth of goblet or columnar neoplastic cells with abundant intracytoplasmic mucin. We report here the cytologic features of PMA in a bronchial brushing specimen. The patient is an 84-year-old woman with a persistent dense consolidation in the right middle lobe of the lung found on non-contrast computed tomography (CT) scan. Bronchial brushing smears showed a monotonous population of columnar neoplastic cells forming "drunken honeycomb"-like cell clusters. The neoplastic cells displayed inconspicuous cytologic atypia. The concurrent transbronchial tissue biopsy and the resection specimen confirmed the diagnosis of PMA. Due to the bland nuclear features, the neoplastic cells in the bronchial brushing specimen were interpreted as benign at the time of the initial diagnosis, demonstrating a diagnostic pitfall of bronchial brushing cytology. A high index of suspicion is recommended when a lung lesion with "drunken honeycomb"-like cell clusters is encountered in bronchial brushing specimens. The review of the literature regarding the recently designated PMA is presented.

Primary pulmonary mucinous cystadenocarcinoma: a case report

Primary pulmonary mucinous cystadenocarcinoma (PMCAC) is an extremely rare cystic neoplasm. A case of a 56-year-old male with a cystic lesion of the right lower lobe is described. Preoperative fine needle aspiration cytology and bronchoscopy were inconclusive. The patient underwent a formal right lower lobectomy and mediastinal lymph node dissection. Diagnosis was established intraoperatively. The biological behavior of primary PMCAC is unknown. Therefore, careful long-term follow-up is considered necessary because of lack of experience globally.

International association for the study of lung cancer/american thoracic society/european respiratory society international multidisciplinary classification of lung adenocarcinoma

INTRODUCTION

Adenocarcinoma is the most common histologic type of lung cancer. To address advances in oncology, molecular biology, pathology, radiology, and surgery of lung adenocarcinoma, an international multidisciplinary classification was sponsored by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society. This new adenocarcinoma classification is needed to provide uniform terminology and diagnostic criteria, especially for bronchioloalveolar carcinoma (BAC), the overall approach to small nonresection cancer specimens, and for multidisciplinary strategic management of tissue for molecular and immunohistochemical studies.

METHODS

An international core panel of experts representing all three societies was formed with oncologists/pulmonologists, pathologists, radiologists, molecular biologists, and thoracic surgeons. A systematic review was performed under the guidance of the American Thoracic Society Documents Development and Implementation Committee. The search strategy identified 11,368 citations of which 312 articles met specified eligibility criteria and were retrieved for full text review. A series of meetings were held to discuss the development of the new classification, to develop the recommendations, and to write the current document. Recommendations for key questions were graded by strength and quality of the evidence according to the Grades of Recommendation, Assessment, Development, and Evaluation approach.

RESULTS

The classification addresses both resection specimens, and small biopsies and cytology. The terms BAC and mixed subtype adenocarcinoma are no longer used. For resection specimens, new concepts are introduced such as adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) for small solitary adenocarcinomas with either pure lepidic growth (AIS) or predominant lepidic growth with ≤ 5 mm invasion (MIA) to define patients who, if they undergo complete resection, will have 100% or near 100% disease-specific survival, respectively. AIS and MIA are usually nonmucinous but rarely may be mucinous. Invasive adenocarcinomas are classified by predominant pattern after using comprehensive histologic subtyping with lepidic (formerly most mixed subtype tumors with nonmucinous BAC), acinar, papillary, and solid patterns; micropapillary is added as a new histologic subtype. Variants include invasive mucinous adenocarcinoma (formerly mucinous BAC), colloid, fetal, and enteric adenocarcinoma. This classification provides guidance for small biopsies and cytology specimens, as approximately 70% of lung cancers are diagnosed in such samples. Non-small cell lung carcinomas (NSCLCs), in patients with advanced-stage disease, are to be classified into more specific types such as adenocarcinoma or squamous cell carcinoma, whenever possible for several reasons: (1) adenocarcinoma or NSCLC not otherwise specified should be tested for epidermal growth factor receptor (EGFR) mutations as the presence of these mutations is predictive of responsiveness to EGFR tyrosine kinase inhibitors, (2) adenocarcinoma histology is a strong predictor for improved outcome with pemetrexed therapy compared with squamous cell carcinoma, and (3) potential life-threatening hemorrhage may occur in patients with squamous cell carcinoma who receive bevacizumab. If the tumor cannot be classified based on light microscopy alone, special studies such as immunohistochemistry and/or mucin stains should be applied to classify the tumor further. Use of the term NSCLC not otherwise specified should be minimized.

CONCLUSIONS

This new classification strategy is based on a multidisciplinary approach to diagnosis of lung adenocarcinoma that incorporates clinical, molecular, radiologic, and surgical issues, but it is primarily based on histology. This classification is intended to support clinical practice, and research investigation and clinical trials. As EGFR mutation is a validated predictive marker for response and progression-free survival with EGFR tyrosine kinase inhibitors in advanced lung adenocarcinoma, we recommend that patients with advanced adenocarcinomas be tested for EGFR mutation. This has implications for strategic management of tissue, particularly for small biopsies and cytology samples, to maximize high-quality tissue available for molecular studies. Potential impact for tumor, node, and metastasis staging include adjustment of the size T factor according to only the invasive component (1) pathologically in invasive tumors with lepidic areas or (2) radiologically by measuring the solid component of part-solid nodules.

Primary pulmonary mucinous cystadenocarcinoma presenting as a complex bronchocele: a case report

Introduction

Primary pulmonary mucinous cystadenocarcinoma is a rare variety of lung cancer. It is characterized pathologically by copious mucin production predominantly in the extracellular space. This tumour has a remarkably favorable prognosis.

Case presentation

We present imaging and histopathological findings of primary pulmonary mucinous cystadenocarcinoma presenting as a complex bronchocele in a 67-year-old Caucasian woman.

Conclusion

Diagnosis of pulmonary mucinous cystadenocarcinoma should be considered in patients presenting with bronchocele that has suspicious imaging features, because the results of fine needle aspiration cytology and bronchoscopy are frequently inconclusive in these tumours. Positive emission tomography has an important role in helping to identify these tumours.

Mucinous cystic neoplasms of the mesentery: a case report and review of the literature

Background

Mucinous cystic neoplasms arise in the ovary and various extra-ovarian sites. While their pathogenesis remains conjectural, their similarities suggest a common pathway of development. There have been rare reports involving the mesentery as a primary tumour site.

Case presentation

A cystic mass of uncertain origin was demonstrated radiologically in a 22 year old female with chronic abdominal pain. At laparotomy, the mass was fixed within the colonic mesentery. Histology demonstrated a benign mucinous cystadenoma.

Methods and results

We review the literature on mucinous cystic neoplasms of the mesentery and report on the pathogenesis, biologic behavior, diagnosis and treatment of similar extra-ovarian tumors. We propose an updated classification of mesenteric cysts and cystic tumors.

Conclusion

Mucinous cystic neoplasms of the mesentery present almost exclusively in women and must be considered in the differential diagnosis of mesenteric tumors. Only full histological examination of a mucinous cystic neoplasm can exclude a borderline or malignant component. An updated classification of mesenteric cysts and cystic tumors is proposed.

Fine-needle aspiration cytology of pulmonary mucinous cystadenocarcinoma

A 64-year-old man presented with symptoms of a lung infection. Radiologic work-up revealed opacity in the upper lobe of right lung. A computer tomographic (CT) guided fine-needle aspiration biopsy revealed sheets and clusters of mild to moderately atypical epithelial cells, small amount of mucin, histiocytes, multinucleated giant cells, and stromal fragments. The differential diagnosis included an inflammatory process and a well-differentiated adenocarcinoma. A lobectomy was performed and revealed abundant extracellular mucin surrounded partially by a thick fibrous wall, which was lined by neoplastic glandular cells. The histology was consistent with a pulmonary mucinous cystadenocarcinoma. Fibroblastic proliferation and foreign-body giant reaction secondary to extravasation of mucin were also noted. The patient was disease free 1 year after initial diagnosis. The relative lack of mucin as well as the presence of well-differentiated neoplastic cells, the inflammatory response to extravasated mcuin constitutes a potential pitfall in recognizing pulmonary mucinous cystadenocarcinoma cytologically.

Diverse histologic appearances in pulmonary mucinous cystic neoplasia: a case report

INTRODUCTION

Primary pulmonary mucinous cystic neoplasia comprises a group of tumors, from benign cystadenoma to mucinous cystadenocarcinoma.

CASE PRESENTATION

We report a case of primary pulmonary mucinous cystadenocarcinoma in a 75-year-old woman who was found to have a right hilar mass on a routine chest X-ray. A lobectomy was performed and the resection specimen revealed a multicystic mucinous tumor. Microscopically, the tumor was composed of confluent mucin-filled cystic spaces lined by columnar mucin-secreting cells which ranged from cytologically bland to moderately atypical with 'bronchioloalveolar pattern' invasion into the adjacent parenchyma. Immunohistochemically, tumor cells were positive diffusely for Cytokeratin 7, and focally for Cytokeratin 20 and Thyroid Transcription Factor-1.

CONCLUSION

This case highlights the continuous spectrum of pulmonary mucinous cystic neoplasia from benign mucinous cystadenoma to malignant mucinous cystadenocarcinoma, and the probable existence of a 'borderline' mucinous cystic tumor. Although molecular data are lacking to substantiate progression from benign to malignant in these neoplasms, the importance of recognizing the morphologic continuum lies in alerting pathologists to thoroughly examine specimens to rule out invasive foci in tumors with 'borderline' morphology.

Benign Tumors and Tumorlike Conditions of the Lung

Context.—Benign tumors and tumorlike conditions of the lung are encountered in the pathologic evaluation of asymptomatic and symptomatic lung nodules. Since many of these lesions are uncommon, they can be diagnostically challenging.

Objective.—To review the current classification of benign lung tumors, with emphasis on histopathology and useful ancillary studies.

Data Sources.—The current World Health Organization classification system for lung neoplasms and review of relevant publications.

Conclusions.—Despite improved imaging techniques, benign lung nodules are encountered in wedge biopsy and resection specimens. Histopathology, immunohistochemistry, and molecular techniques ensure accurate pathologic diagnosis and have shed light on the histogenesis of these unusual lesions.

Pulmonary mucinous cystadenocarcinoma: an extremely rare tumor presenting as a cystic lesion of the lung

Pulmonary mucinous cystadenocarcinoma (PMC) is a rare tumor characterized by mucin production. It is similar to tumors of the same name arising in the ovaries and pancreas. Here we describe the 20th case of PMC reported in the English literature. The patient was a 75-year-old woman with a 3-day history of bloody sputum. Chest radiography and computed tomography revealed a cavitary mass 5 cm in diameter in the posterior segment of the right lung. 18F-fluorodeoxyglucose positron emission tomography demonstrated intense uptake in the wall of the lesion. Right lower lobectomy was performed, and the pathology examination revealed this tumor to be a PMC. The preoperative serum CA 19-9 level was 162.3 U/ml (cutoff 37 U/ml) and decreased to 22.8 U/ml after resection. No mutation of epidermal growth factor receptor or K-ras gene was detected. Thoracic surgeons should bear in mind this rare tumor for the differential diagnosis of a pulmonary cystic lesion.