Basaloid squamous cell lung carcinoma | |
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Specialty | Oncology |
Basaloid squamous cell carcinoma (Bas-SqCC) is an uncommon histological variant of lung cancer composed of cells exhibiting cytological and tissue architectural features of both squamous cell lung carcinoma and basal cell carcinoma. [1]
Lung cancer is a large and exceptionally heterogeneous family of malignancies. [2] Over 50 different histological variants of lung cancer are explicitly recognized within the fourth (2004) revision of the World Health Organization Classification of Lung Tumours ("WHO-2004"). [1] Many of these entities are quite rare, have only been recently described, and remain poorly understood. [3]
Basaloid forms of lung carcinoma were first described in the peer-reviewed medical literature by Dr. Elisabeth Brambilla and her colleagues in 1992. [4]
In the third revision of the World Health Organization lung tumor typing and classification scheme, published in 1999, basaloid variants of both squamous cell lung carcinoma (SqCC) and large cell lung carcinoma (LCLC) were recognized as distinct entities. [3] In the fourth revision (2004) of the WHO system (currently the world standard) Bas-SqCC is classified as one of four recognized variants of squamous cell lung carcinoma. [1] As a variant of SqCC, it is considered a non-small cell lung cancer (NSCLC).
Both basaloid and squamous cell carcinomas have been shown to arise from pre-malignant lesions of dysplasia in the airways of the lung. [5]
Like other forms of lung cancer, Bas-SqCC is ultimately diagnosed after a pathologist examines a tumor sample containing viable malignant cells and tissue under a light microscope and identifies certain particular characteristics. [6]
In the case of Bas-SqCC, it is essential that both evidence of squamous differentiation (i.e., intercellular bridges, production of keratin, tonofilament bundles) and basaloid architecture (i.e. prominent peripheral palisading of cell nuclei, organoid/lobular structures) are identified to make a correct diagnosis. [3] [7]
Immunohistochemical markers that have been suggested to be useful in making an accurate diagnosis of Bas-SqCC include positivity for p63 and high molecular weight keratin (i.e. 34betaE12), and lack of expression of thyroid transcription factor-1 (TTF-1). [8] [9] [10]
Among other pulmonary malignancies, the main differential diagnoses in suspected cases of Bas-SqCC include the high-grade neuroendocrine carcinomas, such as small cell carcinoma and large cell neuroendocrine carcinoma. The issue of differential diagnosis is particularly acute when the pathologist must use a small biopsy specimen or cytology. [9] [10] In addition, the basaloid variant of SqCC can be difficult to distinguish from other poorly differentiated squamous cell carcinomas. [11]
For last several decades of the 20th century, all histological variants of NSCLC were generally treated identically. In the last decade, it has become apparent that different variants of malignant tumors generally exhibit diverse genetic, biological, and clinical properties, including response to treatment. [12] [13]
As patients with uncommon lung tumor variants, including tumors composed of mixtures of histological subtypes, tend to be excluded from clinical trials, [14] the most efficacious treatment regimen(s) for basaloid squamous cell carcinoma remain unknown. In general, these variants appear to be treated according to standard protocols in place for squamous cell carcinoma. [15]
Like nearly all other forms of NSCLC, the prognosis of basaloid squamous cell carcinoma is quite poor. [16]
Although case numbers tend to be rather small, and the published studies statistically underpowered, much (but not all) [15] evidence suggests that basaloid squamous cell lung carcinomas may have a somewhat worse prognosis than "conventional" (i.e. non-basaloid) squamous cell lung carcinomas. [7] [17] [18] As survival has been noted to be worse in basaloid variants at earlier tumor stages (i.e. Stages I and II), the decreased survival could be attributable to earlier distant metastasis appearing during the natural history of these tumors, as compared to other squamous cell carcinomas and NSCLCs in general. [7]
The true incidence and prevalence of basaloid squamous cell lung carcinoma remains unknown, but this form of lung cancer is considered relatively uncommon. [17] In one of the largest studies of this particular variant, Moro-Sibilot and co-workers found a 6.3% prevalence of Bas-SqCC among 1,418 consecutive NSCLC patients at their institution. [7]
Basaloid carcinomas of the lung - like nearly all recognized variants of lung cancer - are highly associated with tobacco smoking. [7] Basaloid architecture in pulmonary carcinomas has been shown to be particularly prevalent in smokers with heavy exposure, [7] and squamous cell carcinoma has the strongest association with tobacco exposure than any other major cell type of NSCLC. [19]
As compared to other forms of lung cancer, Bas-SqCC often occurs in those who are somewhat older than average. [7]
Basaloid squamous cell carcinoma usually begins centrally, in the larger proximal bronchi. [17] Basaloid carcinoma primary in the lung may also occur in a multicentric form. [20]
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.
Large-cell lung carcinoma (LCLC), or large-cell carcinoma (LCC) in short, is a heterogeneous group of undifferentiated malignant neoplasms that lack the cytologic and architectural features of small cell carcinoma and glandular or squamous differentiation. LCC is categorized as a type of NSCLC that originates from epithelial cells of the lung. LCLC is histologically characterized by the presence of large, undifferentiated cells that lack distinctive features of either squamous cell carcinoma or adenocarcinoma. Typically seen in LCLC tumor cells are abundant pale staining cytoplasm and prominent nucleoli.
Combined small cell lung carcinoma is a form of multiphasic lung cancer that is diagnosed by a pathologist when a malignant tumor, arising from transformed cells originating in lung tissue, contains a component of;small cell lung carcinoma (SCLC), admixed with one components of any histological variant of non-small cell lung carcinoma (NSCLC) in any relative proportion.
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.
Targeted therapy of lung cancer refers to using agents specifically designed to selectively target molecular pathways responsible for, or that substantially drive, the malignant phenotype of lung cancer cells, and as a consequence of this (relative) selectivity, cause fewer toxic effects on normal cells.
HOHMS is the medical acronym for "Higher-Order HistoMolecular Stratification", a term and concept which was first applied to lung cancer research and treatment theory.
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.
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).
Adenosquamous lung carcinoma (AdSqLC) is a biphasic malignant tumor arising from lung tissue that is composed of at least 10% by volume each of squamous cell carcinoma (SqCC) and adenocarcinoma (AdC) cells.
Salivary gland–like carcinomas of the lung generally refers a class of rare cancers that arise from the uncontrolled cell division (mitosis) of mutated cancer stem cells in lung tissue. They take their name partly from the appearance of their abnormal cells, whose structure and features closely resemble those of cancers that form in the major salivary glands of the head and neck. Carcinoma is a term for malignant neoplasms derived from cells of epithelial lineage, and/or that exhibit cytological or tissue architectural features characteristically found in epithelial cells.
Large-cell neuroendocrine carcinoma of the lung, or pulmonary large-cell neuroendocrine carcinoma (PLCNC), is a highly malignant neoplasm arising from transformed epithelial cells originating in tissues within the pulmonary tree. It is currently considered to be a subtype of large-cell lung carcinoma.
Basaloid large cell carcinoma of the lung, is a rare histological variant of lung cancer featuring certain distinctive cytological, tissue architectural, and immunohistochemical characteristics and clinical behavior.
Squamous-cell carcinoma (SCC) of the lung is a histologic type of non-small-cell lung carcinoma (NSCLC). It is the second most prevalent type of lung cancer after lung adenocarcinoma and it originates in the bronchi. Its tumor cells are characterized by a squamous appearance, similar to the one observed in epidermal cells. Squamous-cell carcinoma of the lung is strongly associated with tobacco smoking, more than any other forms of NSCLC.
Pulmonary neuroendocrine tumors are neuroendocrine tumors localized to the lung: bronchus or pulmonary parenchyma.
The term squamous-cell carcinoma (SCC), also known as epidermoid carcinoma, comprises a number of different types of cancer that begin in squamous cells. These cells form on the surface of the skin, on the lining of hollow organs in the body, and on the lining of the respiratory and digestive tracts.