Molecular Classification Outperforms Histologic Classification in Prognostication of High-grade Endometrial Carcinomas With Undifferentiated and Sarcomatous Components.

Since the establishment of 4 molecular subgroups of endometrial carcinoma (EC), there has been significant interest in understanding molecular classification in the context of histologic features and diagnoses. ECs with undifferentiated, spindle, and/or sarcomatous components represent a diagnostically challenging subset of tumors with overlapping clinical and histologic features. We examined the clinicopathologic, morphologic, immunohistochemical, and molecular features of these tumors identified in our institutions' pathology databases using immunohistochemistry and targeted sequencing. Disease-specific survival (DSS) and progression-free survival (PFS) were analyzed using Kaplan-Meier curves and log-rank tests. One hundred sixty-two ECs were included: carcinosarcomas (UCS; n=96), dedifferentiated/undifferentiated EC (DDEC/UDEC; n=49), and grade 3 endometrioid EC with spindled growth (GR3spEEC) (n=17). All molecular subgroups were represented in all histologic subtypes and included 12 (7%) POLE -mutated ( POLE mut), 43 (27%) mismatch repair-deficient (MMRd), 77 (48%) p53-abnormal (p53abn), and 30 (19%) no specific molecular profile (NSMP) tumors. However, the molecular classification (irrespective of histologic diagnosis) was a significant predictor for both DSS ( P =0.008) and P≤0.0001). POLE mut EC showed an excellent prognosis with no recurrences or deaths from the disease. MMRd tumors also showed better outcomes relative to NSMP and p53abn tumors. In conclusion, molecular classification provides better prognostic information than histologic diagnosis for high-grade EC with undifferentiated and sarcomatous components. Our study strongly supports routine molecular classification of these tumors, with emphasis on molecular group, rather than histologic subtyping, in providing prognostication.

Molecular Evaluation of Endometrial Dedifferentiated Carcinoma, Endometrioid Carcinoma, Carcinosarcoma, and Serous Carcinoma Using a Custom-Made Small Cancer Panel.

It is often difficult to histologically differentiate among endometrial dedifferentiated carcinoma (DC), endometrioid carcinoma (EC), serous carcinoma (SC), and carcinosarcoma (CS) due to the presence of solid components. In this study, we aimed to categorize these carcinomas according to The Cancer Genome Atlas (TCGA) classification using a small custom-made cancer genome panel (56 genes and 17 microsatellite regions) for integrated molecular diagnosis. A total of 36 endometrial cancer cases with solid components were assessed using IHC, next-generation sequencing (NGS), and the custom-made panel. Among 19 EC cases, six were categorized as MMR-deficient (MMR-d) and eight were classified as having a nonspecific molecular profile. Three EC cases were classified as POLE mutation (POLEmut)-type, which had a very high tumor mutation burden (TMB) and low microsatellite instability (MSI). Increased TMB and MSI were observed in all three DC cases, classified as MMR-d with mutations in MLH1 and POLD1. Except for one case classified as MMR-d, all SC cases exhibited TP53 mutations and were classified as p53 mutation-type. SC cases also exhibited amplification of CCND1, CCNE1, and MYC. CS cases were classified as three TCGA types other than the POLEmut-type. The IHC results for p53 and ARID1A were almost consistent with their mutation status. NGS analysis using a small panel enables categorization of endometrial cancers with solid proliferation according to TCGA classification. As TCGA molecular classification does not consider histological findings, an integrated analytical procedure including IHC and NGS may be a practical diagnostic tool for endometrial cancers.

Clinically relevant molecular subtypes and genomic alteration-independent differentiation in gynecologic carcinosarcoma.

Carcinosarcoma (CS) of the uterus or ovary is a rare, aggressive and biphasic neoplasm composed of carcinoma and sarcoma elements. Previous genomic studies have identified the driver genes and genomic properties associated with CS. However, there is still no molecular subtyping scheme with clinical relevance for this disease. Here, we sequence 109 CS samples, focusing on 596 genes. We identify four molecular subtypes that resemble those observed in endometrial carcinoma: POLE-mutated, microsatellite instability, copy number high, and copy number low subtypes. These molecular subtypes are linked with DNA repair deficiencies, potential therapeutic strategies, and multiple clinicopathological features, including patient outcomes. Multi-regional comparative sequencing reveals genomic alteration-independent CS cell differentiation. Transcriptome and DNA methylome analyses confirm epithelial-mesenchymal transition as a mechanism of sarcoma differentiation. The current study thus provides therapeutic possibilities for CS as well as clues to understanding the molecular histogenic mechanism of its development.

Molecular classification and subtype-specific drug sensitivity research of uterine carcinosarcoma under multi-omics framework.

OBJECTIVE: Uterine carcinosarcomas (UCSs) are aggressive rare tumors recognized as malignancies composed of metaplastic transformation of epithelial elements. Nay no comprehensive molecular classification has been applied to UCS to guide targeted therapies so far, which motivated us to subtyping UCS by aggregating multiple genomic platform data. METHODS: We classified UCS into three distinct subtypes with different clinicopathologic and molecular characterization by using similarity network fusion under consensus clustering framework (SNFCC+) to aggregate four genomic data platforms of 55 UCS patients. Differences across subtypes were extracted by functional enrichment, gene mutations and clinical features. Subtypes were further distinguished by putative biomarkers. We also determined associations between individual oncogenes and chemotherapeutics to discuss subtype-specific drug sensitivity. RESULTS: Functional enrichment analysis of the subtype-specific differential expression genes endowed three subtypes new designation: Myo, Cell and Hormone. Mutations in PTEN, PIK3CA, ARID1A and PPP2R1A altered across subtypes. The epithelial-to-mesenchymal transition (EMT) score distinguished Myo from another two subtypes whereby a high EMT scores prevalently existed and each case was judged as M (mesenchymal) phenotype in Myo subtype. Through the drug sensitivity analysis, we found that the response to - tinib drugs is quite different across subtypes according to expression level. Additionally, different subtypes' response to broad-spectrum anti-cancer drug paclitaxel may be also different. CONCLUSIONS: In this study, we identified three distinct molecular subtypes of UCS with different features. Subtypes were also revealed to have different sensitivity to existing chemotherapy drugs, which may support in-depth study of subtype-specific dosing regimens.

Ultrastaging of Sentinel Lymph Nodes in Endometrial Carcinoma According to Use of 2 Different Methods.

Sentinel lymph node (SLN) sampling may provide staging information without exposing patients to risks of lymph node dissection. There is no consensus protocol for optimal pathologic handling of these specimens. This study compares 2 ultrastaging protocols of SLN in endometrial carcinoma (EC). All SLN were serially sectioned perpendicular to the long axis in 2 mm intervals and entirely submitted for routine hematoxylin and eosin (H&E) processing. SLN negative by routine processing had ultrastaging (US) by one of the following: method 1 (M1), 5 H&E levels at 250 µm intervals with 2 unstained slides at each level; pankeratin immunohistochemistry (IHC) performed on level 1 in cases with negative H&E levels or method 2 (M2), 1 H&E level + 2 unstained slides cut 250 µm into the tissue block; pankeratin IHC performed in cases with negative H&E. Histologic subtype, numbers of SLN, positive SLN, non-SLN, positive non-SLN, and metastasis size were recorded. A total of 178 patients had 527 SLNs (1-16 per case; median, 2 SLN) sampled during hysterectomy for the following EC histotypes: endometrioid International Federation of Gynecology and Obstetrics grade 1/2, 117 (66%); endometrioid International Federation of Gynecology and Obstetrics grade 3, 18 (10%); serous, 20 (11%); carcinosarcoma, 11 (6%); clear cell, 9 (5%); and undifferentiated, 3 (2%). In all, 172 patients had ultrastaging: M1=65; M2=58. In total, 33 patients were SLN positive. Twenty-seven had SLN submitted for US: M1=11; M2=16. Eleven patients had additional SLN detected by US: M1=5; M2=6. Of these, 8 were patients whose SLN were only detected by US representing an increase of 32% in number of patients with positive SLN. Six patients (M1=2; M2=4) with negative SLN had a positive non-SLN. Mean size of ultrastage-detected metastasis was 0.24 mm for M1 and 0.38 mm for M2. Statistical analysis comparing M1 and M2 detected no statistically significant associations with respect to number of positive SLN detected, size of metastasis or false-negative rate and method. The methods performed similarly for both low-grade and high-grade EC. A more comprehensive US protocol had no significant advantages over a single wide interval and IHC in this study population. A pankeratin IHC stain enhances metastasis detection. Additional studies are required to further test this limited protocol as well as to evaluate the clinical significance of the low volume disease detected by ultrastaging.

Histological heterogeneity and distributional difference of gastric carcinosarcoma: report of 4 cases and literature review.

Carcinosarcoma is a rare malignant neoplasm, consisting of both epithelial and mesenchymal component. Primary gastric carcinosarcoma is rare and poorly understood. We reported clinicopathologic features of 4 cases and analysis of 76 cases published in the literature. Clinical symptoms were nonspecific with epigastric pain, weight loss, and melena, as the most common complaints. The prognosis of patients was dismal with high mortality. The tumor commonly occurred in the upper stomach in Chinese patients, whereas, it was more prevalent at the lower stomach in Japanese and other populations. The two malignant components of this rare cancer showed considerable histological heterogeneity with a wide range of differentiation. We propose that carcinosarcomas be divided in two main subtypes: conventional carcinosarcoma and carcinosarcoma, not-otherwise-specified (NOS). Such distinction may provide useful information for targeted treatment of various sarcomatous components of this tumor. Immunohistochemistry should be routinely applied in the diagnosis of this rare tumor.

Time trends in the incidence of hysterectomy-corrected overall, type 1 and type 2 endometrial cancer in Denmark 1978-2014.

OBJECTIVE: To investigate time trends in the incidence of overall, type 1 and type 2 endometrial cancer in Denmark 1978-2014, correcting for hysterectomy. METHODS: Based on the Danish Cancer Registry and the Danish National Patient Registry we calculated hysterectomy-corrected incidence rates of overall, type 1 and type 2 endometrial cancer. Separate analyses for women <55years (defined as pre- and perimenopausal age) and women aged ≥55years (defined as postmenopausal age) and analyses allowing for different time trends before and after the study period midyear 1996 were performed. Log-linear Poisson models were used to estimate annual percentage change (APC) in incidence with 95% confidence intervals (CI). RESULTS: The overall incidence of endometrial cancer decreased slightly from 1978 to 1995, but in the last two decades of the study period the incidence has been stable (APC=0.16; 95% CI: -0.19; 0.50). In the study period (1978-2014) type 1 endometrial cancer incidence decreased slightly (APC=-0.67; 95% CI:-0.83; -0.52), whereas the incidence of type 2 endometrial cancer increased substantially (APC=4.85; 95% CI: 4.47; 5.23). The decrease in type 1 endometrial cancer was most pronounced before 1996 in women younger than 55 years (APC=-2.79; 95% CI: -3.65; -1.91), while the largest increase in type 2 endometrial cancer was observed after 1996 (APC=6.42; 95% CI: 5.72; 7.12). CONCLUSIONS: Over a period of more than 35 years, the incidence of type 1 endometrial cancer decreased, mainly in pre- and perimenopausal women, while type 2 endometrial cancer incidence increased.

Molecular classification of pulmonary sarcomatoid carcinomas suggests new therapeutic opportunities.

BACKGROUND: Pulmonary sarcomatoid carcinoma (SC) is a rare disease with poor prognosis and with strong inter- and intratumor heterogeneity. However, molecular classification is currently focused on activating MET mutations. We sought to better characterize the molecular diversity of SC using mutational signatures that reflect different mutational processes, such as tobacco-associated adducts (signature 4), BRCA1/BRCA2 deficiency (signature 3), or APOBEC enzyme deamination (signatures 2 and 13). PATIENTS AND METHODS: Whole-exome sequencing was carried out in 15 SC patients and on data from 10 previously published cases. Hierarchical clustering and consensus non-negative matrix factorization were carried out for samples classification based on mutational signatures. RESULTS: In the two series, SC distributed between two clusters (C): Csig4 (characterized by signature 4) and Csig2-3-13 (signatures 2, 3, and 13). Csig4 exhibited more frequent MAPK pathway mutations than Csig2-3-13 (pooled series: n = 10/14 versus 2/11, P < 0.05, respectively) and stronger PD-L1 expression (our series: n = 6/9 versus 1/6, P = 0.12). MET alterations were only found in Csig2-3-13 (pooled series: n = 5/11 versus 0/14, P = 0.009), as well as BRCA1/BRCA2 (n = 3/11 versus 0/15), EGFR (n = 1), and IDH1 (n = 1) mutations. Csig2-3-13 patients had better overall survival than Csig4 patients (median: >45 versus 7 months, respectively, P = 0.001). CONCLUSIONS: Our study suggests that SC presents at least two clusters comprising different mutational processes, gene alterations, and PD-L1 expression. New potential treatment possibilities are immune checkpoint inhibitors in Csig4 and specific targeted agents in Csig2-3-13. These findings should encourage clinicians to conduct broad molecular and immunological testing in SC patients beyond MET exon 14 alterations.

Spindle cell and pleomorphic ("sarcomatoid") carcinomas of the lung: an immunohistochemical analysis of 86 cases.

Spindle cell and pleomorphic carcinomas are currently grouped among sarcomatoid carcinomas of the lung. Because of their unusual occurrence, these tumors have not been properly assessed by immunohistochemistry. We performed a comprehensive immunohistochemical analysis of 86 of these tumors. Seventy-four pleomorphic carcinomas (57 with differentiated elements) and 12 spindle cell carcinomas were subjected to immunohistochemistry with CAM5.2, cytokeratin (CK) 7, thyroid transcription factor 1, napsin A, CK5/6, p40, desmocollin 3, Sox2, calretinin, and D2-40. The percentage of positive tumor cells as well as the staining intensity were evaluated and scored. The spindle/giant elements were positive for CAM5.2 (93%), CK7 (79%), thyroid transcription factor 1 (41%), napsin A (20%), calretinin (20%), Sox2 (13%), CK5/6 (9%), p40 (8%), D2-40 (6%), and desmocollin 3 (3%). Of 29 cases in which immunohistochemistry was performed on spindle/giant cell and corresponding differentiated elements, 21 (72%) showed a consistent staining pattern in both components, whereas in 8 cases (28%), the immunophenotype in the spindle/giant cells was less lineage-specific than in the differentiated component. Therefore, we consider that 42% of neoplasms otherwise classified as sarcomatoid carcinoma can be reclassified as adenocarcinoma and 14% as squamous cell carcinoma, while the remaining 44% failed to show a more specific immunophenotype. The use of a comprehensive immunohistochemical panel allows reclassification of the majority of sarcomatoid carcinomas as poorly differentiated variants of adenocarcinoma or squamous cell carcinoma. Such reclassification will facilitate clinical management and allow molecular testing and pursuit of targeted treatment strategies. Application of immunohistochemistry should become the standard in the workup of pulmonary sarcomatoid carcinomas.

[Grading of lung cancer]. / Grading von Lungenkarzinomen.

In comparison with other tumor entities there is no common generally accepted grading system for lung cancer with clearly defined criteria and clinical relevance. In the recent fourth edition of the World Health Organization (WHO) classification from 2015 of tumors of the lungs, pleura, thymus and heart, there is no generally applicable grading for pulmonary adenocarcinomas, squamous cell carcinomas or rarer forms of carcinoma. Since the new IASLC/ATS/ERS classification of adenocarcinomas published in 2011, 5 different subtypes with significantly different prognosis are proposed. This results in an architectural (histologic) grading, which is usually applied to resection specimens. For squamous cell carcinoma the number of different histological subtypes in the new WHO classification was reduced compared to earlier versions but without a common grading system. In recent publications nesting and budding were proposed as the main (histologic) criteria for a grading of squamous cell carcinomas. The grading of neuroendocrine tumors (NET) of the lungs in comparison with NET in other organs is presented in a separate article in this issue. Certain rare tumor types are high grade per definition: small cell, large cell and pleomorphic carcinomas, carcinosarcomas and pulmonary blastomas. In the future it is to be expected that these developments will be further refined, e. g. by adding further subtypes for adenocarcinomas and cytologic and/or nuclear criteria for adenocarcinoma and/or squamous cell carcinomas.

A suggested modification to FIGO stage I endometrial cancer.

OBJECTIVE: FIGO stage I endometrial cancers are divided into two substages, regardless of the presence or absence of lymphovascular space invasion (LVSI). The aim of this study was to investigate whether stratification based on the LVSI status would better predict mortality. METHODS: Using a multicentric database, we identified patients who underwent endometrial cancer operations between 2000 and 2010. The staging performance was quantified with respect to discrimination. RESULTS: The study cohort included 508 patients (198 with LVSI-positive tumors and 310 with LVSI-negative tumors). The survival difference between the stage I patients with LVSI-positive and LVSI-negative tumors was highly significant (81% and 97%, respectively P=.009), whereas the difference between the stage I patients with tumors invading greater or less than half of the myometrium was not (87% and 96%, respectively P=0.09). The 5-year OS rates for the patients with LVSI-negative tumors invading less than half of the myometrium, with LVSI-negative tumors invading more than half of the myometrium and with LVSI-positive invading more than or less than half of the myometrium were 98%, 95%, and 81%, respectively (P=.03). Separating the LVSI-negative and LVSI-positive tumors would improve discrimination (concordance index, 77% vs. 75%, respectively, using the actual staging system). CONCLUSION: A LVSI-positive status has a significantly worse prognosis. In this study, the distinction by LVSI status appears to be more relevant than the distinction between stages IA and IB for predicting survival in stage I endometrial cancer. This difference in prognosis would favor restaging these two entities.

High-grade endometrial carcinomas - strategies for typing.

High-grade endometrial carcinomas are subject to low rates of interobserver diagnostic agreement; this may be a result of the existence of morphologically ambiguous carcinomas, many of which are microsatellite instability-high. High-grade endometrial carcinomas with prototypic morphology have characteristic genotypes and immunohistochemical profiles. Assays accounting for these features may be applied to morphologically ambiguous carcinomas in the hope that the results will provide some clarity about a tumour's origin and expected clinical outcome, and even whether tumour progression has occurred. It is important to be able to demonstrate that morphologically based diagnoses are strongly linked not only to clinical outcomes, but also to genetic signatures and expression profiles. There are still numerous persistent problems in tumour classification that will require a critical evaluation of the type and strength of evidence needed to refine diagnostic algorithms.

Use of mutation profiles to refine the classification of endometrial carcinomas.

The classification of endometrial carcinomas is based on pathological assessment of tumour cell type; the different cell types (endometrioid, serous, carcinosarcoma, mixed, undifferentiated, and clear cell) are associated with distinct molecular alterations. This current classification system for high-grade subtypes, in particular the distinction between high-grade endometrioid (EEC-3) and serous carcinomas (ESC), is limited in its reproducibility and prognostic abilities. Therefore, a search for specific molecular classifiers to improve endometrial carcinoma subclassification is warranted. We performed target enrichment sequencing on 393 endometrial carcinomas from two large cohorts, sequencing exons from the following nine genes: ARID1A, PPP2R1A, PTEN, PIK3CA, KRAS, CTNNB1, TP53, BRAF, and PPP2R5C. Based on this gene panel, each endometrial carcinoma subtype shows a distinct mutation profile. EEC-3s have significantly different frequencies of PTEN and TP53 mutations when compared to low-grade endometrioid carcinomas. ESCs and EEC-3s are distinct subtypes with significantly different frequencies of mutations in PTEN, ARID1A, PPP2R1A, TP53, and CTNNB1. From the mutation profiles, we were able to identify subtype outliers, ie cases diagnosed morphologically as one subtype but with a mutation profile suggestive of a different subtype. Careful review of these diagnostically challenging cases suggested that the original morphological classification was incorrect in most instances. The molecular profile of carcinosarcomas suggests two distinct mutation profiles for these tumours: endometrioid-type (PTEN, PIK3CA, ARID1A, KRAS mutations) and serous-type (TP53 and PPP2R1A mutations). While this nine-gene panel does not allow for a purely molecularly based classification of endometrial carcinoma, it may prove useful as an adjunct to morphological classification and serve as an aid in the classification of problematic cases. If used in practice, it may lead to improved diagnostic reproducibility and may also serve to stratify patients for targeted therapeutics.

High SUVmax on FDG-PET indicates pleomorphic subtype in epithelioid malignant pleural mesothelioma: supportive evidence to reclassify pleomorphic as nonepithelioid histology.

BACKGROUND: We have recently proposed to reclassify the pleomorphic subtype of epithelioid malignant pleural mesothelioma (MPM) as nonepithelioid (biphasic/sarcomatoid) histology because of its similarly poor prognosis. We sought to investigate whether preoperative maximum standardized uptake value (SUVmax) on F-fluorodeoxyglucose (FDG) positron emission tomography (PET) correlates with histologic subtype in MPM. METHODS: Clinical data were collected for 78 patients with MPM who underwent preoperative FDG-PET. We retrospectively classified the epithelioid tumors into five subtypes: trabecular, tubulopapillary, micropapillary, solid, and pleomorphic. Tumors were categorized by SUVmax into two groups: low (<10.0) and high (≥10.0). RESULTS: The median overall survival of epithelioid tumors with high SUVmax (n = 12) was significantly shorter (7.1 months) than that of epithelioid tumors with low SUVmax (n = 54, 18.9 months, p < 0.001) and comparable to nonepithelioid tumors (n = 12, 7.2 months). Epithelioid tumors with pleomorphic subtype (n = 9) had marginally higher SUVmax (mean ± SD: 10.6 ± 5.9) than epithelioid nonpleomorphic subtype (n = 57, 6.5 ± 3.2, p = 0.050), and were comparable to that of nonepithelioid tumors (n = 12, 9.1 ± 4.8). Among the epithelioid tumors with high SUVmax (n = 12), 50% (n = 6) showed pleomorphic subtype. In contrast, among epithelioid tumors with low SUVmax (n = 54), 6% (n = 3) showed epithelioid pleomorphic subtypes (p = 0.001). A positive correlation between mitotic count and SUVmax was observed (r = 0.30, p = 0.010). CONCLUSIONS: Pleomorphic subtype of epithelioid MPM showed higher SUVmax than the epithelioid nonpleomorphic subtype and was similar to nonepithelioid histology. Preoperative SUVmax on FDG-PET in epithelioid MPM can indicate patients with pleomorphic subtype with poor prognosis, supporting their reclassification as nonepithelioid.

[Malignant odontogenic tumors]. / Maligne odontogene Tumoren.

Malignant odontogenic tumors are extremely rare. As with benign odontogenic tumors, malignant epithelial odontogenic tumors or odontogenic carcinomas are distinguished from the even rarer mesenchymal ones, the odontogenic sarcomas. The existence of odontogenic carcinosarcomas is not yet acknowledged by the World Health Organization. Odontogenic carcinomas comprise ameloblastic carcinoma (AmCa), primary intraosseous carcinoma (PIOC), clear cell odontogenic carcinoma, odontogenic ghost cell carcinoma (OGCC), and the special case of metastasizing ameloblastoma. Odontogenic sarcomas consist of ameloblastic fibrosarcoma and ameloblastic fibrodentinosarcoma and fibroodontosarcoma. Whereas metastasizing ameloblastoma can be diagnosed only after having metastasized, all other malignant odontogenic tumors present with atypia, increased cellularity and mitoses, and invasion. Odontogenic sarcomas are regarded as low-grade tumors that rarely metastasize. Odontogenic carcinomas, however, especially AmCa, OGCC, and PIOC, are more aggressive, with a 5-year survival rate of about 70% for AmCa and OGCC and a 3-year survival rate of about 37% for PIOC. Radical surgery, eventually in combination with radiotherapy, is the treatment of choice.

Molecular genetic findings in two cases of sarcomatoid carcinoma of the ureter: evidence for evolution from a common pluripotent progenitor cell?

The current World Health Organization classification recommends the usage of the term sarcomatoid carcinoma (SC) for all biphasic malignant neoplasms of the urinary tract exhibiting morphologic and/or immunohistochemical evidence of epithelial and mesenchymal differentiation. While most SC have been described in the urinary bladder, ureteral SC are extremely rare tumors. Here, we report on the clinical, morphological, and molecular biological findings of two cases in this unusual location. The genetic alterations investigated by comparative genomic hybridization in the epithelial and the mesenchymal component of both cases showed considerable but not complete overlap. Moreover, in spite of many morphological differences between the two cases, both cases shared some genetic gains and losses. Our findings are compatible with the concept that SC originates from a common pluripotent progenitor cell with a potential for epithelial and mesenchymal differentiation.

Cutaneous carcinosarcoma: adnexal vs. epidermal types define high- and low-risk tumors. Results of a meta-analysis.

OBJECTIVE: We report four cases of cutaneous carcinosarcoma (CS) and perform a meta-analysis of the cutaneous CS literature. RESULTS: CS occurred in elderly patients (mean of 80 years) on sun-damaged skin, and were keratotic papules of short duration. They did not recur after excision. CS exhibited basal cell carcinoma mixed with atypical fibroxanthoma cell populations. Immunophenotyping revealed vimentin+/keratin- spindle cells and vimentin-/keratin+ epithelial cells. Three cases exhibited p53 protein expression of both carcinomatous and sarcomatous components. Literature review identified 38 cases of cutaneous CS that could be broadly classified into two distinct groups. Epidermal-derived (basal or squamous cell carcinoma epithelial component) CS arose on the sun-damaged skin of the head and neck of elderly males (mean age 72 years) and had a 70% 5-year disease-free survival. In contrast, adnexal CS (spiradenocarcinoma, porocarcinoma, proliferating tricholemmal cystic carcinoma, or matrical carcinoma) occurred in younger patients (mean age 58 years), showed recent growth in a long-standing nodule and had a 25% 5-year disease-free survival. Age less than 65 years, recent growth, long-standing skin tumor, and tumor size greater than 2 cm significantly correlated with poor outcome. CONCLUSIONS: Cutaneous CS is an aggressive skin cancer with high risk for advanced disease. Significant risk factors exist whose identification will allow for better management of CS patients.