Evaluation of the relationship between adenosarcoma and carcinosarcoma and a hypothesis of the histogenesis of uterine sarcomas

Mixed Endometrioid Adenocarcinoma and Müllerian Adenosarcoma of the Uterus and Ovary: Clinicopathologic Characterization With Emphasis on its Distinction From Carcinosarcoma

Mullerian adenosarcoma is a biphasic neoplasm composed of benign or atypical Müllerian epithelium and a malignant mesenchymal component that is usually, but not always, of low grade. Focal architectural or cytologic atypia of the epithelial component resembling atypical hyperplasia may uncommonly be present and foci of adenocarcinoma have been rarely reported. Whether the coexistence of these 2 tumor components is a result of independent primaries (collision tumor), adenocarcinoma arising from the epithelial component of the adenosarcoma, an unusual form of carcinosarcoma or some other mechanism is uncertain. To establish the diagnostic criteria and clinical significance of the coexistence of adenocarcinoma in close association with Müllerian adenosarcoma, we conducted a multi-institutional study of these rare tumors. Twenty-six patients were identified with "mixed" adenosarcoma and adenocarcinoma; they ranged in age from 43 to 87 years (median: 66 y). Tumors occurred in the uterine corpus (n=22), ovary (n=2), and the pelvis (n=2). All but 6 had International Federation of Gynecology and Obstetrics (FIGO) stage I disease. All extrauterine tumors were associated with endometriosis. The tumor size ranged from 2 to 25 cm (median: 7.9 cm). The sarcomatous component was of low grade in 18 and high grade in 8 (the majority demonstrating rhabdomyoblastic differentiation); 9 had stromal overgrowth. Twenty-five carcinomas were endometrioid in type (23 FIGO grade 1; 3 FIGO grade 2) and 1 carcinoma was dedifferentiated with FIGO grade 1 endometrioid adenocarcinoma component; 33% of the uterine neoplasms were associated with adjacent endometrial hyperplasia. Next-generation sequencing in 2 tumors identified similar molecular abnormalities in the sarcomatous and carcinomatous components supporting a clonal relationship. Of 10 patients with available follow-up (median: 18 mo), 8 had no evidence of disease and 2 died of recurrent sarcoma at 7 and 8 months. Endometrioid adenocarcinomas that arise in close spatial association with Müllerian adenosarcoma appear to be clonally related to the sarcoma. Unlike carcinosarcomas, these tumors are usually early stage at presentation. The prognosis appears to be driven by the sarcomatous component. These tumors should be distinguished from carcinosarcomas, dedifferentiated endometrial carcinomas, and corded and hyalinized endometrioid carcinomas.

Genomic profiling identifies GPC5 amplification in association with sarcomatous transformation in a subset of uterine carcinosarcomas

Uterine carcinosarcoma, also known as Malignant Mixed Müllerian Tumour, is a high‐grade biphasic neoplasm composed of sarcomatous elements thought to originate via transdifferentiation from high‐grade endometrial carcinoma. To identify molecular factors contributing to the histogenesis of this tumour, we analyzed DNA extracted from matched carcinoma and sarcoma components from 12 cases of carcinosarcoma by a molecular inversion probe microarray to assess genomic copy number alterations (CNAs) and allelic imbalances. Widespread CNAs were identified in tumours with serous histology in the carcinoma component (9/12), while the remaining three cases with endometrioid carcinoma were near‐diploid. Quantification of the extent of genomic aberrations revealed a significant increase in sarcoma relative to carcinoma in tumours with well‐delineated histologic components. Focal amplification of 13q31.3 was identified in 6/12 profiled tumours, of which four harboured the aberration exclusively in the sarcoma component. This result was verified by fluorescence in situ hybridization against GPC5, the only gene situated within the minimal region of amplification. In a validation cohort composed of 97 carcinosarcomas and other uterine sarcomas, amplification of GPC5 (GPC5/CEP13 ratio ≥ 2.2) was identified in 11/97 (11.3%) cases (9/64 carcinosarcoma, 1/3 rhabdomyosarcoma, 1/21 leiomyosarcoma, 0/8 adenosarcoma, 0/1 undifferentiated endometrial sarcoma) and an additional 4 (2.8%) cases had low level gains (GPC5/CEP13 ratio ≥1.5 but <2.2). The functional relevance of Glypican‐5, the gene product of GPC5, in regulating differentiation and lineage commitment was demonstrated in an endometrial carcinoma cell line in vitro. In conclusion, we identified GPC5 amplification as a molecular event mediating epithelial‐mesenchymal transdifferentiation in a subset of uterine carcinosarcomas.

Pathology of Endometrial Carcinoma

On a clinicopathological and molecular level, two distinctive types of endometrial carcinoma, type I and type II, can be distinguished. Endometrioid carcinoma, the typical type I carcinoma, seems to develop through an estrogen-driven "adenoma carcinoma" pathway from atypical endometrial hyperplasia/endometrioid intraepithelial neoplasia (AEH/EIN). It is associated with elevated serum estrogen and high body mass index and expresses estrogen and progesterone receptors. They are mostly low grade and show a favorable prognosis. A subset progresses into high-grade carcinoma which is accompanied by loss of receptor expression and accumulation of TP53 mutations and behaves poorly. Other frequently altered genes in type I carcinomas are K-Ras, PTEN, and ß-catenin. Another frequent feature of type I carcinomas is microsatellite instability mainly caused by methylation of the MLH1 promoter. In contrast, the typical type II carcinoma, serous carcinoma, is not estrogen related since it usually occurs in a small uterus with atrophic endometrium. It is often associated with a flat putative precursor lesion called serous endometrial intraepithelial carcinoma (SEIC). The molecular pathogenesis of serous carcinoma seems to be driven by TP53 mutations, which are present in SEIC. Other molecular changes in serous carcinoma detectable by immunohistochemistry involve cyclin E and p16. Since many of the aforementioned molecular changes can be demonstrated by immunohistochemistry, they are useful ancillary diagnostic tools and may further contribute to a future molecular classification of endometrial carcinoma as recently suggested based on The Cancer Genome Atlas (TCGA) data.

A practical approach to the diagnosis of mixed epithelial and mesenchymal tumours of the uterus

The current 2014 World Health Organization (WHO) Classification of mixed epithelial and mesenchymal tumours of the uterus includes categories of carcinosarcoma, adenosarcoma, adenofibroma, adenomyoma and atypical polypoid adenomyoma, the last two lesions being composed of an admixture of benign epithelial and mesenchymal elements with a prominent smooth muscle component. In this review, each of these categories of uterine neoplasm is covered with an emphasis on practical tips for the surgical pathologist and new developments. In particular, helpful clues in the distinction between carcinosarcoma and dedifferentiated endometrial carcinoma will be discussed. In addition, salient features to help distinguish between adenofibroma, adenosarcoma, embryonal rhabdomyosarcoma and other mesenchymal neoplasms in the differential diagnosis will be outlined. Finally, a discussion of adenomyoma and its main differential diagnostic considerations will be covered.

TP53 mutations, tetraploidy and homologous recombination repair defects in early stage high-grade serous ovarian cancer

To determine early somatic changes in high-grade serous ovarian cancer (HGSOC), we performed whole genome sequencing on a rare collection of 16 low stage HGSOCs. The majority showed extensive structural alterations (one had an ultramutated profile), exhibited high levels of p53 immunoreactivity, and harboured a TP53 mutation, deletion or inactivation. BRCA1 and BRCA2 mutations were observed in two tumors, with nine showing evidence of a homologous recombination (HR) defect. Combined Analysis with The Cancer Genome Atlas (TCGA) indicated that low and late stage HGSOCs have similar mutation and copy number profiles. We also found evidence that deleterious TP53 mutations are the earliest events, followed by deletions or loss of heterozygosity (LOH) of chromosomes carrying TP53, BRCA1 or BRCA2. Inactivation of HR appears to be an early event, as 62.5% of tumours showed a LOH pattern suggestive of HR defects. Three tumours with the highest ploidy had little genome-wide LOH, yet one of these had a homozygous somatic frame-shift BRCA2 mutation, suggesting that some carcinomas begin as tetraploid then descend into diploidy accompanied by genome-wide LOH. Lastly, we found evidence that structural variants (SV) cluster in HGSOC, but are absent in one ultramutated tumor, providing insights into the pathogenesis of low stage HGSOC.

Extragenital Müllerian adenosarcoma with pouch of Douglas location

Background

Of all female genital tract tumors, 1-3% are stromal malignancies. In 8-10% of cases, these are represented by Müllerian adenosarcoma an extremely rare tumor characterized by a stromal component of usually low-grade malignancy and by a benign glandular epithelial component. Variant that arises in the pouch of Douglas is scarcely mentioned in the medical literature.

Case Presentation

A 49-year-old para-0 woman, was seen at our OB/GYN-UNIT because she complained vaguely of pelvic pain. She had a mass of undefined nature in the pouch of Douglas. A simple excision of the mass showed low-grade Müllerian adenosarcoma with areas of stromal overgrowth. One and a half year after surgery, at another hospital, a mass was detected in the patient's posterior vaginal fornix and removed surgically. Six months later she came back to our observation with vaginal bleeding and mass in the vaginal fornix. We performed radical surgery. The pathological examination showed recurrent adenosarcoma. Surgical treatment was supplemented by radiation therapy.

Conclusions

The case of Müllerian adenosarcoma reported here is the third known so far in the literature that was located in the pouch of Douglas. To date, only two other such cases have been reported, including one resulting from neoplastic degeneration of an endometriotic cyst.

Long-term outcome and natural history of uterine adenosarcomas

OBJECTIVE

Adenosarcomas are rare tumors composed of a benign epithelium in combination with a malignant mesenchymal component. We examined the natural history of uterine adenosarcomas and compared the outcome of uterine adenosarcoma and carcinosarcoma.

METHODS

Patients with uterine adenosarcomas and carcinosarcomas registered in the Surveillance, Epidemiology, and End Results database between 1988 and 2006 were examined. Survival was analyzed using Cox proportional hazards model and the Kaplan-Meier method.

RESULTS

A total of 5496 patients including 544 (10%) with adenosarcomas were identified. Patients with adenosarcomas tended to be younger and were more likely to have early-stage tumors (p<0.0001) In a multivariate model patients with adenosarcomas were 65% (HR=0.35; 95% CI, 0.28-0.45) less likely to die from their tumors than women with carcinosarcomas. Five-year survival was 79% (95% CI, 75-84%) for stage I adenosarcomas and 51% (95% CI, 49-54%) for carcinosarcomas. For stage III disease, 5-year survival for adenosarcomas was 48% (95% CI, 29-65%) vs. 24% (95% CI, 20-27%) for carcinosarcomas.

CONCLUSION

The majority of women with uterine adenosarcoma present with early-stage tumors and have a favorable outcome. Despite the overall favorable prognosis for most patients, survival is only 63-69% for women whose tumors invade into the wall of the uterus and lower than 50% for disease spread beyond the uterus.

Mullerian adenosarcoma of the female genital tract

Mullerian adenosarcoma is an uncommon, but not rare, mixed tumor containing a neoplastic but benign or mildly atypical epithelial element and a sarcomatous, usually low-grade, stromal component. The most common site is the uterine corpus but adenosarcoma also occurs in the cervix and ovary and more rarely in the vagina, fallopian tube, arising from peritoneal surfaces, or outside the female genital tract, for example in the intestine. Most uterine cases have a polypoid gross appearance, sometimes resulting in the formation of multiple polyps. Characteristic histologic features include a low power "phyllodes-like" architecture with leaf-like projections lined by a variety of benign Mullerian type epithelia, sometimes with squamous metaplasia. Intraglandular stromal protrusions are a characteristic feature. The stroma may be uniformly cellular but there is typically increased cellularity around the epithelial elements, resulting in the formation of a cambium layer. Using the World Health Organization definition, stromal mitotic activity of 2 or more per 10 high-power fields is required for a diagnosis of adenosarcoma but in practice the diagnosis is made with stromal mitotic activity less than this if the characteristic architecture and cambium layer is present. The stromal component is usually morphologically "low-grade" and of endometrial stromal or fibroblastic type (hormone receptor and CD10 positive). Sometimes it is high grade, resembling undifferentiated sarcoma. Additional features sometimes present include heterologous stromal elements or sex cord-like differentiation. Uterine adenosarcomas are, in general, low-grade neoplasms capable of local recurrence after polypectomy or hysterectomy and much less commonly distant metastasis. The 2 most important adverse prognostic factors, which sometimes coexist, are deep myometrial invasion and sarcomatous overgrowth; the latter is usually associated with morphologically "high-grade" stromal elements with loss of expression of hormone receptors and CD10. Adenosarcoma may be confused with a variety of lesions and one of the main differential diagnoses is adenofibroma in which the stromal component is, by definition, morphologically benign. However, occasional adenofibromas recur or even metastasize. As such, it has been suggested that all adenofibromas should be classified as adenosarcomas, albeit with low-malignant potential. Ovarian adenosarcomas are much more likely to exhibit malignant behavior than their uterine counterparts, probably due to the lack of an anatomic barrier to peritoneal dissemination.

Mixed Müllerian Tumors of the Female Genital Tract

Malignant mixed müllerian tumor (MMMT) and müllerian/mesodermal adenosarcoma are 2 of the most common mixed müllerian tumors of the female genital tract. MMMT is a biphasic neoplasm, composed of morphologically malignant epithelial and stromal components. MMMT should be distinguished from endometrioid adenocarcinoma with spindle cell elements, "dedifferentiated" endometrioid carcinoma, and combined adenocarcinoma and neuroendocrine carcinoma. Adenosarcoma is also biphasic; it is composed of morphologically benign or low-grade appearing epithelial components and malignant stromal components. The differential diagnosis of adenosarcoma includes MMMT, endometrial stromal tumor containing endometrioid glands, benign endometrial or endocervical polyp, adenofibroma, adenomyoma, including atypical polypoid adenomyoma, botryoid embryonal rhabdomyosarcoma (sarcoma botryoides), and endometriosis, including polypoid endometriosis. Gross and microscopic features, including immunophenotype, should permit discrimination of the various entities.

Mullerian adenosarcomas: an immunophenotypic analysis of 35 cases

Mullerian adenosarcomas (MAs) are rare mixed mesenchymal and epithelial neoplasms that occur most commonly in the uterus. Although the epithelial component is typically benign, the mesenchymal component of most adenosarcomas morphologically resembles that observed in endometrial stromal tumors and is responsible for their clinical behavior. Thus, the differential diagnosis usually includes not only low-grade endometrial stromal tumors, but also adenofibroma, carcinosarcoma, and embryonal rhabdomyosarcoma especially in small samples. The objective of this study was to ascertain the immunophenotypic profile of the epithelial and mesenchymal components of MAs and delineate possible differences between conventional mesenchymal areas and areas of sarcomatous overgrowth. Representative sections from 35 MAs, 28 of them without sarcomatous overgrowth (MA-NSO) and 7 with sarcomatous overgrowth (MA-SO), were included in the study. Thirty tumors arose in the uterus, 4 were pelvic, and 1 originated in the colon. Adequate blocks were selected and immunostained for estrogen receptor (ER), progesterone receptor (PR), androgen receptor (AR), CD10, WT1, smooth muscle actin, desmin, AE1/3 cytokeratin, CD34, calretinin, inhibin, c-kit, and Ki-67. The mesenchymal component expressed ER in 21/27 MA-NSOs but in only 1/7 MA-SOs (65% overall). PR was expressed in 21/26 MA-NSOs and 4/7 MA-SOs (76% overall), whereas AR was positive in 10/27 MA-NSOs and 5/7 MA-SOs (35% overall). CD10 was expressed in 23/28 MA-NSOs but in only 2/7 MA-SOs (71% overall), and WT1 positivity was seen in 22/27 MA-NSOs and 6/7 MA-SOs (79% overall). Sixty-seven percent of MAs expressed smooth muscle actin, 32% desmin, including both examples of MA-SOs with rhabdomyoblastic differentiation, and 25% expressed AE1/3 cytokeratin. CD34 expression was found in 35% of the tumors, but it was almost always patchy in distribution and weak in intensity, as was calretinin expression, seen only in 12% of the cases. Expression of c-kit and inhibin in greater than 5% of the tumor cells was not encountered. The median and mean Ki-67 labeling indices were 10% and 12%, respectively (range, <5% to 40%). The median and mean Ki-67 indices were both 5% in MA-NSOs compared with 30% and 28%, respectively, in MA-SOs. The epithelial compartment demonstrated expression for ER (24/32), PR (23/31), and AE1/3 cytokeratin (33/33); rare cases expressed CD10 (4 cases) and AR (1 case). In summary, the immunophenotype of most MAs resembled that of endometrial stromal tumors (positive for ER, PR, WT1, and CD10, with variable expression of muscle markers, AR and cytokeratin). The proliferative rate in the stromal component was strongly related to the presence of sarcomatous overgrowth. ER, PR, and CD10 expression was lost in MA-SOs relative to conventional low-grade stromal areas of mullerian/mesodermal adenosarcomas, reflecting the "dedifferentiation" of this component.

Pathology of uterine malignancies

This overview covers epithelial, stromal and mesenchymal malignancies of the body of the uterus, excluding the cervix. The distinction of type I and type II endometrial adenocarcinoma with the morphological variants of this tumour is discussed and some molecular aspects are explored. The concept of carcinosarcoma representing a metaplastic adenocarcinoma of the endometrium that behaves more like a carcinoma than a sarcoma is explained. Some types of mixed epithelial and stromal neoplasm are described and contrasted with carcinosarcoma. The concept of stromal sarcoma and high-grade uterine sarcoma is described and an outline of malignant smooth muscle tumours of the uterus includes a description of smooth muscle tumours of uncertain malignant potential and worrying benign smooth muscle lesions.

Characterization of a newly established uterine carcinosarcoma cell line featuring the sarcomatous phenotype of the tumor in vitro

We describe the newly established cell line CS-99 derived from a uterine carcinosarcoma retaining features of the sarcomatous phenotype in vitro. CS-99 cells exhibit a mesenchymal morphology with predominantly spindle-shaped cells at nonconfluence turning to pleomorphic appearance at confluence. The mesenchymal phenotype was evidenced immunohistochemically by strong vimentin and moderate SM-actin, which was similar to the sarcomatous component of the primary tumor. P53 was overexpressed in a subset of CS-99 cells. Epithelial membrane antigen was moderately expressed whereas other markers including pan CK, CK 5/6, CK 34, epidermal growth factor receptor, desmin, carcinoembryonic antigen, S100, KIT, ERBB2, and the hormone receptors, estrogen receptor and progesterone receptor revealed either weak or no specific staining in CS-99 cells. High self-renewal capacity corresponded to the population doubling time of 23 h in high passage. CS-99 cells were able to develop three-dimensional tumor spheroids in vitro. Cytogenetic analysis and multicolor fluorescence in situ hybridization of CS-99 demonstrated an almost stable karyotype including numerical changes +8, +18, and +20 and translocations, amongst others der(1)t(1;2), der(1)t(1;7), der(2)t(2;19), der(5)t(5;8), and der(5)t(5;14). Taken together, the cell line CS-99 exhibits strong growths dynamics and a complex but stable karyotype in higher passages, and can be further a useful in vitro model system for studying tumor biology of carcinosarcomas.

Central nervous system involvement from malignant mixed Müllerian tumor (MMMT) of the uterus

The central nervous system is traditionally considered as an uncommon site for metastatic disease from the female genital tract, and cerebral metastasis as the primary manifestation of an occult gynecological malignancy is even more rare. Here, we report the case of a 61-year-old female who presented with neurological symptoms of confusion, headache, cerebellar ataxia and right-sided weakness. Magnetic resonance imaging of the brain revealed two solid lesions in the frontal lobe and the left cerebellar hemisphere. Endometrial biopsy of a uterine mass detected during search for the primary lesion showed malignant mixed Müllerian tumor (MMMT). The patient refused surgery. Cranial radiotherapy for progressive cerebral disease led to resolution of her neurological symptoms. Two months after the diagnosis of MMMT the patient died from local complications of advanced pelvic disease. At autopsy, only the epithelial component of the tumor had metastasized to the brain. Attention should be paid to possibility of unusual distant metastases associated to MMMT in order to avoid delay in diagnosis and treatment of these patients.

Primary bone carcinosarcoma: Chondrosarcoma and squamous cell carcinoma with keratin pearl formation

Malignant bone tumors with epithelial differentiation are extremely rare. Only one case of primary malignant bone tumor with distinct squamous cell carcinoma and chondrosarcoma has ever been reported. Reported herein is a case of primary malignant bone tumor with distinct squamous cell carcinoma and chondrosarcoma, so-called carcinosarcoma of bone, arising in the femur of a 53-year-old man. The tumor was located within the femur and was diagnosed by curettage as a well-differentiated chondrosarcoma. No primary tumor was detected in any other organ. Within a few months the tumor had rapidly grown toward the soft tissue, and hemipelvectomy was performed. Examination of the surgical specimen revealed that the tumor was mainly composed of undifferentiated spindle sarcoma cells with scattered foci of chondrosarcoma and of squamous cell carcinoma with keratin pearl formation. The patient died approximately 6 months postoperatively. At autopsy multiple metastases were detected in the heart, both lungs, muscles, and lymph nodes. Interestingly, the chondrosarcoma and squamous cell carcinoma components were observed in several metastatic foci. The tumors in both the previously reported case and the present case contained components of chondrosarcoma and squamous cell carcinoma with keratin pearl formation, and this combination of histological features may be a unique characteristic of carcinosarcoma of bone.

Carcinosarcoma Arising in a Patient with Multiple Cylindromas

Familial cylindromatosis (Brooke-Spiegler syndrome) is a rare autosomal dominant inherited disease characterized by the development of adnexal tumors, mostly cylindromas, but also trichoepitheliomas and spiradenomas. Malignant tumors may occur, usually with the features of a cylindrocarcinoma. The authors describe the case of a 75-year-old woman with the Brooke-Spiegler syndrome who presented with multiple nodules of the scalp, face, and trunk. In 1997 she underwent surgical excision of the entire forehead and scalp with skin grafting. Histologic examination revealed multiple cylindromas, some with areas of spiradenoma and one with an extensive adenomatous component; some trichoepitheliomas were also evident. In 2002, a nodule of the trunk suddenly increased in size and became painful. The lesion was excised and histologic and immunohistochemical evaluation revealed a malignant cutaneous biphasic tumor extending into the subcutis, consisting of a major portion with the features of an adnexal carcinoma and of a minor one of atypical spindle cells. Biphasic malignant skin tumors are rare and only a limited number have been described, none in association with the Brooke-Spiegler syndrome. The authors discuss the morphogenesis of the folliculosebaceous-apocrine unit from which the tumors in this syndrome derive, and the pivotal role of mesenchymal cells in determining the process. Since the Brooke-Spiegler syndrome is characterized by a germline mutation in the CYLD oncosuppressor gene, a biphasic tumor in this setting may represent a true carcinosarcoma.

Genomic aberrations in carcinomas of the uterine corpus

Endometrial carcinoma, the most common invasive neoplasm of the female genital tract, occurs either in a hormone-related, less virulent form (type I) or in a hormone-independent, more aggressive form (type II). Another cancer of the uterine corpus is carcinosarcoma, a biphasic or mixed epithelial-mesenchymal tumor, now classified as metaplastic carcinoma. We examined by karyotyping and comparative genomic hybridization a consecutive series of 67 endometrial carcinomas and 15 carcinosarcomas and compared the cytogenetic features of the different carcinoma subtypes. All three subtypes of uterine carcinoma had in common a nonrandom gain of material from 1q and 8q but differed from one another in other respects. Endometrial carcinomas of type I mostly presented gains from chromosome arms 1q and 8q and losses from Xp, 9p, 9q, 17p, 19p, and 19q, whereas endometrial carcinomas of type II showed a more complex imbalance picture, with gains from chromosome arms 1q, 2p, 3q, 5p, 6p, 7p, 8q, 10q, and 20q and losses from Xq, 5q, and 17p. The carcinosarcomas mostly showed gains of or from 1q, 5p, 8q, and 12q but losses from 9q, that is, they were much more similar to endometrial carcinomas in their pattern of acquired genomic changes than to sarcomas of the uterine corpus. It was also possible to identify different copy number changes among the different grades of type I carcinomas, between serous papillary and clear-cell carcinomas of type II, as well as between homologous and heterologous carcinosarcomas. Specifically, type I adenocarcinomas that were highly differentiated mostly showed gains from 1q and 10p; those that were moderately differentiated showed gains from 1q, 7p, 7q, and 10q as well as losses from Xp, 9p, 9q, 17p, 19p, and 19q; whereas those poorly differentiated showed gains from 1q, 2p, 2q, 3q, 6p, 8q, and 20q but losses from Xp, Xq, 5q, 9p, 9q, 17p, and 17q. The serous papillary carcinomas showed gains from 1q, 2p, 2q, 3q, 5p, 6p, 6q, 7p, 8q, 18q, 20p, and 20q but losses from 17p, whereas the clear-cell carcinomas showed gains from 3q, 7p, 8q, 10q, 16p, and 20q but losses from 6q. Finally, the homologous carcinosarcomas presented gains from 1p, 1q, 8q, 12q, and 17q as well as losses from 9q and 13q, whereas the heterologous tumors showed gains from 1q, 8p, and 8q. The reproducibility of the observed correlations between karyotypic aberration patterns and histological differentiation was underscored by the fact that those carcinosarcomas whose epithelial component resembled type I endometrial carcinomas also exhibiting a type I aberration profile, whereas carcinosarcomas with a type II carcinoma differentiation had karyotypic abnormalities similar to those of type II endometrial carcinomas.

Tumor classification: molecular analysis meets Aristotle

Background

Traditionally, tumors have been classified by their morphologic appearances. Unfortunately, tumors with similar histologic features often follow different clinical courses or respond differently to chemotherapy. Limitations in the clinical utility of morphology-based tumor classifications have prompted a search for a new tumor classification based on molecular analysis. Gene expression array data and proteomic data from tumor samples will provide complex data that is unobtainable from morphologic examination alone. The growing question facing cancer researchers is, "How can we successfully integrate the molecular, morphologic and clinical characteristics of human cancer to produce a helpful tumor classification?"

Discussion

Current efforts to classify cancers based on molecular features ignore lessons learned from millennia of experience in biological classification. A tumor classification must include every type of tumor and must provide a unique place for each tumor within the classification. Groups within a classification inherit the properties of their ancestors and impart properties to their descendants. A classification was prepared grouping tumors according to their histogenetic development. The classification is simple (reducing the complexity of information received from the molecular analysis of tumors), comprehensive (providing a place for every tumor of man), and consistent with recent attempts to characterize tumors by cytogenetic and molecular features. The clinical and research value of this historical approach to tumor classification is discussed.

Summary

This manuscript reviews tumor classification and provides a new and comprehensive classification for neoplasia that preserves traditional nomenclature while incorporating information derived from the molecular analysis of tumors. The classification is provided as an open access XML document that can be used by cancer researchers to relate tumor classes with heterogeneous experimental and clinical tumor databases.