Metaplastic carcinoma

Although once the most common type of NSCLC, squamous cell (or epidermoid) carcinoma now accounts for less than 30% of all lung cancers, and is distinguished histologically by evidence of squamous differentiation. This tumor tends to be central in origin, arising from metaplastic bronchial epithelium, and frequently extends into the bronchial lumen, resulting in obstruction. Squamous cell carcino-... 

Smith KJ, Skelton 3rd HG, Morgan AM, et al. Spindle cell neoplasms coexpressing cytokeratin and vimentin (metaplastic squamous cell carcinoma). J Cutan Pathol. 1992 19 286-... 

In the pancreas, squamous cells can be encountered in injured ductal epithelium as a result of a metaplastic process. The same metaplastic phenomenon also seems to take place focally in some examples of DA. When this finding is prominent (>25% of the tumor is the cut-off the authors use), the tumor is classified as adenosquamous carcinoma, and if it is exclusively squamous, then squamous cell carcinoma.Most of the tumors express CKs (CAM 5.2, AE1/AE3, CK5/6, CK7, CKS, CK13, CK18, CK19, and CK20), EMA, CA19-9, CEA, and B72.3.i7Ti76 Typically, CK5/6,... 

FIGURE 18 15 p53 and Ki-67 can be useful for distinguishing endometrial surface metaplastic and degenerative changes from endometrial intraepithelial carcinoma (EIC). EIC (A-Q contrasts with metaplastic-degenerative change (D-F) by virtue of uniform and intense nuclear expression for p53 (B versus E) and Ki-67 (C versus F) in EIC. 

It has been proposed that studying CDIO expression could help to distinguish invasive endometrial cancer from adenocarcinomas that colonize adenomyosis. " Since CDIO expression is characteristic of endometrial stroma and not myometrial smooth muscle, the theory goes that CDIO expression surrounding adenocarcinoma in the myometrium would support adenomyosis over invasive carcinoma. Unfortunately, there are at least two problems with this idea. It turns out that many invasive adenocarcinomas are surrounded by a rim of tissue that expresses CDIO, such that the appearance mimics the endometrial stroma that one expects in adenomyosis. A less common problem involves metaplastic stroma. In occasional endometrial cancers, endometrial stroma supporting endometrial cancer undergoes metaplasia to a smooth muscle or fibroblastic phenotype, similar to the stroma that is characteristic of endometrial polyps. This metaplastic stroma frequently expresses CDIO only weakly or focally. Therefore, absent CDIO staining does not entirely exclude the presence of endometrial stroma and adenomyosis. 

Recently p63, a homologue of the tumor suppressor protein p53, has gained use as a multi-tasker in multiple organs for the detection of MECs, basal cells (prostate), and myoepithelial differentiation (breast metaplastic carcinoma and salivary gland tumors) and as a marker for squamous differentiation. 78,29 advantage of... 

Metaplastic Carcinoma—Use of Keratins, Melanoma, and Vascular Markers... 

Metaplastic carcinoma comprises a group of heterogeneous neoplasms that exhibit pure epithelial or mixed epithelial and mesenchymal phenotypes. Diag-... 

TABLE 19.4 Metaplastic Carcinoma versus Spindle Cell Sarcoma of the Breast 1 ... 

Basal cytokeratins along with p63 are also very sensitive markers for identifying spindle cell metaplastic carcinomas. 

Although muscle differentiation in myoepithelial carcinomas separates them from spindle cell metaplastic carcinomas, they likely represent two different spectra of one entity. 

Davis WG, Hennessy B, Babiera G, et al. Metaplastic sarcomatoid carcinoma of the breast with absent or minimal overt invasive carcinomatous component A misnomer. Am J Surg Pathol. 2005 29 1456-1463. 

Adem C, Reynolds C, Adlakha H, et al. Wide spectrum screening keratin as a marker of metaplastic spindle cell carcinoma of the breast An immunohistochemical study of 24 patients. Histopathology. 2002 40 556-562. 

Koker MM, Kleer CG. p63 expression in breast cancer A highly sensitive and specific marker of metaplastic carcinoma. Am J Surg Pathol. 2004 28 1506-1512. 

Dunne B, Lee AH, Finder SE, et al. An immunohistochemi-cal study of metaplastic spindle cell carcinoma, phyllodes tumor and fibromatosis of the breast. Hum Pathol. 2003 34 1009-1015. 

Leibl S, Gogg-Kammerer M, Sommersacher A, et al. Metaplastic breast carcinomas Are they of myoepithelial differentiation Immunohistochemical profile of the sarcomatoid subtype using novel myoepithelial markers. Am J Surg Pathol. 2005 29 347-... 

Popnikolov NK, Ayala AG, Graves K, et al. Benign myoepithelial tumors of the breast have immunophenotypic characteristics similar to metaplastic matrix-producing and spindle cell carcinomas. Am J Clin Pathol. 2003 120 161-167. 

Reis-Filho JS, Milanezi F, Paredes J, et al. Novel and classic myoepithelial/stem cell markers in metaplastic carcinomas of the breast. Appl Immunohistochem Mol Morphol. 2003 11 1-8. 

Reis-Filho JS, Pinheiro C, Lambros MB, et al. EGFR amplification and lack of activating mutations in metaplastic breast carcinomas. J Pathol. 2006 209 445-453. 

T-cell lymphoma, ALCL, AML, GIST, breast metaplastic carcinoma, ovarian sex cord stromal tumors, synovial sarcoma, Merkel cell carcinoma, endocrine and neuroendocrine tumors, desmoplastic small round cell tumor, melanoma, nephroblastoma, ependymoma, mesenchymal chondrosarcoma, extrarenal malignant rhabdoid tumor, rhabdomyosarcoma, meningeal... 

The ambiguous histological differentiation and the controversial immunophenotype of synovial sarcoma make the microscopic diagnosis difficult, especially when the tumor occurs in atypical locations or when the tumor reveals a non-specific immunohistochemical phenotype, which may resemble the immunophenotypic profile of other malignancies such as different types of sarcoma (solitary fibrous tumor, malignant peripheral nerve sheet tumor, fibrosarcoma, epithelioid sarcoma or leiomyosarcoma), metaplastic carcinoma and mesothelioma. Since synovial sarcoma reveals a different clinical behavior than the other mentioned tumors, it is important to discriminate it from these malignancies and additional methods that are more specific may be necessary to confirm the diagnosis. 

Squamous cell carcinoma is a common malignancy arising in different organs and systems including skin, respiratory, gastro-intestinal- and genito-urinary systems, derived from stratified squamous epithelia or from metaplastic epithelia. 

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