Mucinous cystadenocarcinoma of the lung | |
---|---|
Other names | Mucinous multilocular cyst carcinoma, Pseudomyxomatous pulmonary adenocarcinoma, Mucinous cystic tumor of low malignant potential [1] |
Specialty | Oncology |
Mucinous cystadenocarcinoma of the lung (MCACL) is a very rare malignant mucus-producing neoplasm arising from the uncontrolled growth of transformed epithelial cells originating in lung tissue.
According to the most recent revision (2004) of the World Health Organization (WHO) histological classification system for lung tumors ("WHO2004"), currently the most widely recognized typing scheme for pulmonary neoplasia, MCACL is considered a distinctive variant of adenocarcinoma. [2]
Informally, some experts have included these tumors as a distinct variant among a spectrum of mucus-producing adenocarcinomas, including — in order of increasing relative extent of cellular mucus production and extracellular mucus accumulation — solid adenocarcinoma, mucoepidermoid carcinoma, mucinous bronchioloalveolar carcinoma, signet ring cell adenocarcinoma, mucinous cystadenocarcinoma, and mucinous "colloid" adenocarcinoma. [3]
MCACL has been noted in most cases to show areas of gradual transition wherein cells become more atypical and feature more pronounced characteristics of malignancy as one proceeds from the capsule, or outermost layers of the tumor, toward the center of the mass. [4] Some experts suggest that this tumor often develops after a slow progression from a relatively benign to a frankly malignant phenotype over a period of years to decades. [1]
The putative cell of origin of this tumor is unknown. Electron microscopic studies in 3 cases [5] [6] described intracytoplasmic mucin, convoluted oval nuclei, prominent nucleoli, homogeneous euchromatin with peripheral chromatin condensation, microvilli, junctional complexes, and primitive lumen formation. Their failure to identify lamellar bodies and large dense granules seemed to rule out origination from either Club cells or Type II pneumocytes. [1]
In a review of 66 cystic pulmonary mucinous lesions, Gao and colleagues reported that p53 expression and a Ki-67 index exceeding 20% is characteristic of MCACL. [1]
This particular variant of lung cancer is usually asymptomatic and is found after chest x-rays are taken for other reasons. [7] Hemoptysis is seen occasionally [7] and, in some cases, distal obstruction of bronchi by blood clots or mucus plugs produces cough and/or infection. [1] Lesions often enlarge and progress slowly, over many years. [8]
The 1999 World Health Organization classification system defined MCACL as a cystic adenocarcinoma with copious mucin production that, histologically, resembles (the more common) mucus-producing cystadenocarcinomas originating in the ovary, breast and pancreas. [9] The 2004 revision of the WHO classification noted that the tumors tend to be well circumscribed by a partial fibrous tissue capsule with central cystic change and copious mucin pooling. [2] The thin, fibrous wall circumscribing the tumor is highly characteristic of this lesion. [4] It can sometimes occur within a pulmonary bronchocele, and this tumor entity should be kept in mind after identification of a bronchocele with suspicious or non-prototypical imaging characteristics. [10] [11]
Microscopically, the neoplastic epithelial cells tend to grow along the alveolar walls, in a fashion similar to the mucinous variant of bronchioloalveolar carcinoma, a more common form of adenocarcinoma. [2]
Hemoptysis is seen occasionally. [7]
Positron Emission Tomography (PET) scanning can be of assistance in diagnosing MCACL, [10] as these lesions show intense uptake, typically in the wall of the tumor. [7]
CA 19-9 has been reported to be elevated in MCACL. [7]
Differential diagnosis of MCACL includes secondary metastatic cystadenocarcinomatous lesions, particularly from the pancreas or ovary, mucoepidermoid carcinoma, and pulmonary mucinous bronchioloalveolar carcinoma. [4] [1] [12] The mouse monoclonal antibody 1D3, developed to detect a high molecular weight mucin found in a number of cystic malignancies of various organs, may be of use in differentiating primary mucinous cystadenocarcinoma of the lung from metastatic lung tumors due to mucinous cystic lesions of the uterus and pancreas, as well as those primary in the colon and stomach. [13]
For treatment purposes, MCACL has been traditionally considered a non-small cell lung carcinoma (NSCLC). Complete radical surgical resection is the treatment of choice. [14]
There is virtually no data regarding new molecular targets or targeted therapy in the literature to date. Iwasaki and co-workers failed to find mutations of the epidermal growth factor receptor (EGFR) or the cellular Kirsten rat sarcoma virus oncogene K-ras in one reported case.[ citation needed ]
MCACL has a much more favorable prognosis than most other forms of adenocarcinoma and most other NSCLC's. [10] [14] Cases have been documented of continued growth of these lesions over a period of 10 years without symptoms or metastasis. [8] The overall mortality rate appears to be somewhere in the vicinity of 18% to 27%, depending on the criteria that are used to define this entity. [1]
Accurate incidence statistics on MCACL are unavailable. It is a very rare tumor, [12] with only a few dozen cases reported in the literature to date. [1]
In the few cases described in the literature to date, the male-to-female ratio is approximately unity, and right lung lesions occurred twice as commonly as left lung lesions. Approximately 2/3 of cases have been associated with tobacco smoking. [1] Cases have been reported in patients as young as 29. [8]
Adenocarcinoma is a type of cancerous tumor that can occur in several parts of the body. It is defined as neoplasia of epithelial tissue that has glandular origin, glandular characteristics, or both. Adenocarcinomas are part of the larger grouping of carcinomas, but are also sometimes called by more precise terms omitting the word, where these exist. Thus invasive ductal carcinoma, the most common form of breast cancer, is adenocarcinoma but does not use the term in its name—however, esophageal adenocarcinoma does to distinguish it from the other common type of esophageal cancer, esophageal squamous cell carcinoma. Several of the most common forms of cancer are adenocarcinomas, and the various sorts of adenocarcinoma vary greatly in all their aspects, so that few useful generalizations can be made about them.
Carcinoma is a malignancy that develops from epithelial cells. Specifically, a carcinoma is a cancer that begins in a tissue that lines the inner or outer surfaces of the body, and that arises from cells originating in the endodermal, mesodermal or ectodermal germ layer during embryogenesis.
A serous tumour is a neoplasm that typically has papillary to solid formations of tumor cells with crowded nuclei, and which typically arises on the modified Mullerian-derived serous membranes that surround the ovaries in females. Such ovarian tumors are part of the surface epithelial-stromal tumour group of ovarian tumors. They are common neoplasms with a strong tendency to occur bilaterally, and they account for approximately a quarter of all ovarian tumors.
Surface epithelial-stromal tumors are a class of ovarian neoplasms that may be benign or malignant. Neoplasms in this group are thought to be derived from the ovarian surface epithelium or from ectopic endometrial or Fallopian tube (tubal) tissue. Tumors of this type are also called ovarian adenocarcinoma. This group of tumors accounts for 90% to 95% of all cases of ovarian cancer; however is mainly only found in postmenopausal women with the exception of the United States where 7% of cases occur in women under the age of 40. Serum CA-125 is often elevated but is only 50% accurate so it is not a useful tumor marker to assess the progress of treatment. 75% of women with epithelial ovarian cancer are found within the advanced-stages; however younger patients are more likely to have better prognoses than older patients.
Pseudomyxoma peritonei (PMP) is a clinical condition caused by cancerous cells that produce abundant mucin or gelatinous ascites. The tumors cause fibrosis of tissues and impede digestion or organ function, and if left untreated, the tumors and mucin they produce will fill the abdominal cavity. This will result in compression of organs and will destroy the function of the colon, small intestine, stomach, or other organs. Prognosis with treatment in many cases is optimistic, but the disease is lethal if untreated, with death occurring via cachexia, bowel obstruction, or other types of complications.
Adenocarcinoma in situ (AIS) of the lung —previously included in the category of "bronchioloalveolar carcinoma" (BAC)—is a subtype of lung adenocarcinoma. It tends to arise in the distal bronchioles or alveoli and is defined by a non-invasive growth pattern. This small solitary tumor exhibits pure alveolar distribution and lacks any invasion of the surrounding normal lung. If completely removed by surgery, the prognosis is excellent with up to 100% 5-year survival.
Cystadenocarcinoma is a malignant form of a cystadenoma and is a cancer derived from glandular epithelium, in which cystic accumulations of retained secretions are formed. The neoplastic cells manifest varying degrees of anaplasia and invasiveness, and local extension and metastases occur. Cystadenocarcinomas develop frequently in the ovaries, where pseudomucinous and serous types are recognized. Similar tumor histology has also been reported in the pancreas, although it is a considerably rarer entity representing 1–1.5% of all Pancreatic cancer.
Signet ring cell carcinoma (SRCC) is a rare form of highly malignant adenocarcinoma that produces mucin. It is an epithelial malignancy characterized by the histologic appearance of signet ring cells.
A mucinous neoplasm is an abnormal and excessive growth of tissue (neoplasia) with associated mucin. It arises from epithelial cells that line certain internal organs and skin, and produce mucin. A malignant mucinous neoplasm is called a mucinous carcinoma. For example, for ovarian mucinous tumors, approximately 75% are benign, 10% are borderline and 15% are malignant.
Mucinous cystadenoma is a benign cystic tumor lined by a mucinous epithelium. It is a type of cystic adenoma (cystadenoma).
Intraductal papillary mucinous neoplasm (IPMN) is a type of tumor that can occur within the cells of the pancreatic duct. IPMN tumors produce mucus, and this mucus can form pancreatic cysts. Although intraductal papillary mucinous neoplasms are benign tumors, they can progress to pancreatic cancer. As such IPMN is viewed as a precancerous condition. Once an intraductal papillary mucinous neoplasm has been found, the management options include close monitoring and pre-emptive surgery.
Fetal adenocarcinoma (FA) of the lung is a rare subtype of pulmonary adenocarcinoma that exhibits tissue architecture and cell characteristics that resemble fetal lung tissue upon microscopic examination. It is currently considered a variant of solid adenocarcinoma with mucin production.
Large cell lung carcinoma with rhabdoid phenotype (LCLC-RP) is a rare histological form of lung cancer, currently classified as a variant of large cell lung carcinoma (LCLC). In order for a LCLC to be subclassified as the rhabdoid phenotype variant, at least 10% of the malignant tumor cells must contain distinctive structures composed of tangled intermediate filaments that displace the cell nucleus outward toward the cell membrane. The whorled eosinophilic inclusions in LCLC-RP cells give it a microscopic resemblance to malignant cells found in rhabdomyosarcoma (RMS), a rare neoplasm arising from transformed skeletal muscle. Despite their microscopic similarities, LCLC-RP is not associated with rhabdomyosarcoma.
Epithelial-myoepithelial carcinoma of the lung is a very rare histologic form of malignant epithelial neoplasm ("carcinoma") arising from lung tissue.
Adenocarcinoma of the lung is the most common type of lung cancer, and like other forms of lung cancer, it is characterized by distinct cellular and molecular features. It is classified as one of several non-small cell lung cancers (NSCLC), to distinguish it from small cell lung cancer which has a different behavior and prognosis. Lung adenocarcinoma is further classified into several subtypes and variants. The signs and symptoms of this specific type of lung cancer are similar to other forms of lung cancer, and patients most commonly complain of persistent cough and shortness of breath.
Acinar adenocarcinoma is a histological subtype of gland-forming cancer that is diagnosed when cuboidal and/or columnar shaped malignant cells in the neoplastic tissue form acini and tubules. It is a common form of cancer occurring in the lung and prostate gland.
Sarcomatoid carcinoma of the lung is a term that encompasses five distinct histological subtypes of lung cancer, including (1) pleomorphic carcinoma, (2) spindle cell carcinoma, (3) giant cell carcinoma, (4) carcinosarcoma, or (5) pulmonary blastoma.
Giant-cell carcinoma of the lung (GCCL) is a rare histological form of large-cell lung carcinoma, a subtype of undifferentiated lung cancer, traditionally classified within the non-small-cell lung carcinomas (NSCLC).
Ceruminous adenocarcinoma is a malignant neoplasm derived from ceruminous glands of the external auditory canal. This tumor is rare, with several names used in the past. Synonyms have included cylindroma, ceruminoma, ceruminous adenocarcinoma, not otherwise specified (NOS), ceruminous adenoid cystic carcinoma (ACC), and ceruminous mucoepidermoid carcinoma.
Pulmonary enteric adenocarcinoma is rare subtype of pulmonary adenocarcinoma.