Pleomorphic Component Research Articles

Exceptional Location of a Pleomorphic Leiosarcoma: Clinical Case

Pleomorphic leiomyosarcoma is a rare entity that is part of the pleomorphic sarcomas with a complex genome with a high metastatic capacity and a usually poor prognosis. The most common location remains the lower extremities but other sites have been reported in the literature, particularly in the chest wall. Leiomyosarcoma (LMS) is an exceptionally rare tumor in the chest wall. Classical LMS may exhibit focal areas of pleomorphic cells; however, the coexistence of a large pleomorphic component allows the tumor to be designated as pleomorphic leiomyosarcoma (PLMS). The first cases of pleomorphic leiomyosarcoma were reported in the literature by Brooks in 1985. The pleomorphic component of these tumors is often heterologous with either cartilaginous differentiation; bony or rhabdomyosarcomatous. Since pleomorphic myogenic sarcomas, including high-grade leiomyosarcomas and rhabdomyosarcomas, have a poorer prognosis hence the importance of an accurate and valid histological diagnosis. The thoracic location of a leiomyosarcoma remains exceptional or even extremely rare and management requires multidisciplinary consultation involving the surgeon; the oncologist and the radiotherapist with additional molecular study to properly detect genetic anomalies in order to consider possible targeted therapy.

Mixed adenoneuroendocrine carcinoma of the non-ampullary duodenum with mismatch repair deficiency: a rare case report

A non-ampullary duodenal mixed adenoneuroendocrine carcinoma (MANEC), consisting of a conventional adenocarcinoma and a neuroendocrine carcinoma (NEC), is exceedingly rare. Moreover, mismatch repair (MMR) deficient tumors have recently attracted attention. The patient, a 75-year-old woman with epigastric pain and nausea, was found to have a type 2 tumor of the duodenum, which was diagnosed on biopsy as a poorly differentiated carcinoma. A pancreaticoduodenectomy specimen showed a well-defined 50 × 48 mm tumor in the duodenal bulb, which was morphologically composed of glandular, sheet-like, and pleomorphic components. The glandular component was a tubular adenocarcinoma, showing a MUC5AC-positive gastric type. The sheet-like component consisted of homogenous tumor cells, with chromogranin A and synaptophysin diffusely positive, and a Ki-67 index of 72.8%. The pleomorphic component was diverse and prominent atypical tumor cells proliferated, focally positive for chromogranin A, diffusely positive for synaptophysin, and the Ki-67 index was 67.1%. The sheet-like and pleomorphic components were considered NEC, showing aberrant expression of p53, retinoblastoma, and p16. Notably, all three components were deficient in MLH1 and PMS2. We diagnosed a non-ampullary duodenal MANEC with MMR deficiency. This tumor has a unique morphology and immunohistochemical profile, and is valuable for clarifying the tumorigenesis mechanism of a non-ampullary duodenal MANEC.

An Uncommon Presentation of Carcinosarcoma of the Stomach and a Minimally Invasive Approach for Treatment

Carcinosarcoma is a rare malignant neoplasm that is composed of both epithelial and mesenchymal tumor components. Gastric carcinosarcoma is even more rare and is often diagnosed at a late stage. In this report, we investigate a case of early gastric carcinosarcoma with regional lymph node metastasis in a 78-year-old woman. The patient underwent partial gastrectomy, lymphadenectomy, and splenectomy. The tumor was confined to the gastric submucosa, and a biopsy specimen led to a histological diagnosis of carcinosarcoma with adenocarcinoma, squamous-cell carcinoma, and undifferentiated pleomorphic sarcoma components. Metastasis was present in one lymph node and displayed osteosarcomatous differentiation. Vigilant monitoring for recurrence and metastatic disease will be required for this patient.

PLEOMORPHIC LEIOMYOSARCOMA IN THE ORAL CAVITY

Leiomyosarcoma (LMS) is an exceptionally rare tumor in oral cavity. The classical LMS can present with focal areas of pleomorphic cells; however, the coexistence of large pleomorphic component lets the tumor be designated as pleomorphic leiomyosarcoma (PLMS). This report describes the case of an 18-year-old man complaining of a painful mass in the retromolar area lasting for 15 days. On clinical exam, there was a granulomatous, ulcerated tumor mass extending to the retromolar area. This hyperplastic tissue was removed by incisional biopsy. The histopathologic exam revealed an extremely atypical tumor proliferation, with scarce areas of cells poorly arranged in fascicles and mixture of polygonal, rabhdoid, epithelioid, and spindle cells. Immunohistochemistry included desmin, smooth muscle actin (SMA), h-caldesmon, S-100, vimentin, Ki-67, AE1/AE3, HHF-35, and HMB45. The pleomorphic areas were strongly positive for h-caldesmon and SMA, and negative for the other markers. Treatment consisted of a partial mandibulectomy. The patient died a few months after the surgery. Support: FAPEMIG.

Prostatic Adenocarcinoma With Focal Pleomorphic Giant Cell Features: A Series of 30 Cases.

Prostatic adenocarcinoma with focal pleomorphic giant cell features is rare with the only prior series consisting of 6 cases. From 2005 to 2018, we identified 29 cases from our consult service and 1 case from our own institution. Men ranged in age from 39 to 90 years (median=75.5). Diagnostic specimens consisted of needle biopsies (n=13); transurethral resections (n=7), urethral/bladder biopsies (n=8), radical prostatectomy (n=1), and orchiectomy (n=1). In all cases, there was usual acinar prostatic adenocarcinoma, where the highest grade in all cases was Gleason score 9 to 10 (Grade Group 5). On average, 68% of the involved cores had cancer with a maximum percent of cancer averaging 55%; on average, transurethral resections had 85% of the area involved by cancer. Areas of cancer showing pleomorphic giant cell features were focal (<5%). Two of the needle biopsies showed extraprostatic extension. The radical prostatectomy had seminal vesicle invasion and positive margins with lymphovascular invasion. Prostatic adenocarcinoma with focal pleomorphic giant cell features is always accompanied by extensive usual acinar prostate adenocarcinoma where the highest grade in all cases was Gleason score 9 to 10 (Grade Group 5). Although the pleomorphic component is focal, it can mimic urothelial carcinoma. IHC can be misleading as PSA staining is often negative or focal in both the pleomorphic and usual prostatic adenocarcinoma components. NKX3.1 is the most sensitive prostate marker, but was still focal in 1 usual prostatic adenocarcinoma and negative in 2 pleomorphic components. Prostatic adenocarcinoma with focal pleomorphic giant cell features has a dismal prognosis. In men with no prior diagnosis of prostate adenocarcinoma and >1-year follow-up, 7/19 (37%) were dead at a median of 8 months after diagnosis. Of the 7 men with a prior history of prostate adenocarcinoma, 4/7 (57%) were dead at a median of 7 months after diagnosis of recurrent prostate adenocarcinoma with pleomorphic giant cell features.

Pleomorphic and dedifferentiated leiomyosarcoma: a clinicopathologic analysis

Objective: To investigate the clinicopathologic features, differential diagnosis and biological behavior of pleomorphic leiomyosarcoma (PLMS) and dedifferentiated leiomyosarcoma (DLMS). Methods: Forty-nine cases were collected from November 2007 to December 2016, including eight that diagnosed at Fudan University Shanghai Cancer Center, and 41 consultation cases. The clinical findings and pathologic features were reviewed. Immunophenotype was obtained in 33 cases and follow-up information was available in 38 cases. Results: There were 22 males and 27 females with ages ranging from 24 to 83 years (mean 52.5 years). Fifteen cases occurred in extremities, 14 in deep body cavity, 11 in the trunk, 4 in the head and neck, 2 in the bladder, and 1 each in the inguinal region, perineum and femoral vein, respectively. Tumor sizes ranged from 3 to 30 cm (mean 9.1 cm). The tumors were composed of at least small foci of typical leiomyosarcoma (LMS) and areas of high-grade pleomorphic/undifferentiated sarcoma. The typical LMS component showed the characteristic morphology of smooth muscle differentiation and was low to intermediate grade in most cases. Pleomorphic areas were mainly composed of atypical spindle and polygonal cells admixed with variable large, bizarre atypical cells and multinuclear giant cells, mostly mimicking undifferentiated pleomorphic sarcoma. The pleomorphic and leiomyosarcomatous areas were usually intermixed, but the demarcation may be distinct or gradual in some cases. The classical LMS component was positive for at least one myogenic marker: α-SMA in 97.0%(32/33), desmin in 72.7%(24/33), H-caldesmon in 90.9% (20/22), MSA in 14/16, and calponin in 15/15 of cases. The pleomorphic sarcoma component was reactive for at least one myogenic marker in 87.9% (29/33) of cases, usually showing focal and less intense immunoreactivity than classical LMS component: α-SMA was positive in 81.8%(27/33), desmin in 48.5%(16/33), H-caldesmon in 72.7% (16/22), MSA in 12/16, and calponin in 11/15 of cases. Based on staining for muscle markers in the pleomorphic component, 29 cases were designated as PLMS, 4 as DLMS. Ki-67 index ranged from 15% to 70% (mean 40%). Follow-up data was available in 38 cases (77.6%), of which 11 patients (28.9%) died of disease, 12 patients were alive with unresectable or recurrent disease, 14 patients were alive with no evidence of disease and another one died of unrelated cause. The median disease-free and overall survival was 6 and 10 months respectively. Twelve patients exhibited local recurrence and 11 developed metastases. The median interval to progression was 8 months. Conclusions: The identification of areas of typical LMS is crucial for accurate diagnosis of PLMS and DLMS. Both PLMS and DLMS show more aggressive behavior and poorer prognosis than ordinary LMS.

Rhabdomyosarcoma of the kidney

Abstract Rhabdomyosarcoma is considered the most common soft tissue sarcoma arising in patients younger than 15 years old, accounting for 5%–10% of childhood solid tumors. Sarcoma of the kidney represents 1% of all primary renal malignancies. Primary renal rhabdomyosarcoma is a very rare entity with limited number of cases reported in the literature. In this paper we present two cases of primary renal rhabdomyosarcoma in pediatric patients. The two tumors involved the renal parenchyma and occurred in 2-year-old girl and 6-year-old boy, respectively. Histopathology examination and immunohistochemistry studies confirm the diagnosis of embryonal rhabdomyosarcoma with pleomorphic component, and pleomorphic rhabdomyosarcoma, respectively. Both cases are treated with chemotherapy and show a good response with no evidence of recurrence or metastasis. The aim of this paper is to expand the differential diagnosis of primary mesenchymal kidney tumors in pediatric age group.

Rhabdomyosarcoma with Pseudolipoblasts Arising in Ovarian Carcinosarcoma: A Distinctive Postchemotherapy Morphologic Variant Mimicking Pleomorphic Liposarcoma

We describe a case of ovarian carcinosarcoma occurring in a 60-year-old female. The neoplasm was excised after neoadjuvant chemotherapy and contained a predominant heterologous pleomorphic rhabdomyosarcomatous component in which there were numerous multivacuolated rhabdomyoblasts that strongly mimicked lipoblasts. The clear cell variant of rhabdomyosarcoma is rarely documented, but this case shows a highly unusual finding in which the rhabdomyoblasts show the prominent multivacuolation with nuclear indentation characteristic of and indistinguishable from pleomorphic lipoblasts. This appears to represent a posttreatment phenomenon. As this finding might conceivably occur in other rhabdomyosarcomas after chemotherapy, we highlight the potential for diagnostic confusion with pleomorphic liposarcoma, which is usually diagnosed by morphology so that immunohistochemistry for muscle markers might not be performed.

Primary Squamous Cell Carcinoma of the Breast

Studies evaluating the biological behavior of primary squamous cell carcinoma (SCC) of the breast have yielded inconsistent results, perhaps in part because most studies have not taken into consideration specific histologic subtypes. We identified 21 cases of primary SCC of the breast diagnosed between the years 1985 and 2010 and analyzed the association between particular histologic features and disease outcome. Most tumors (17/21) were moderately or poorly differentiated, and most had a high nuclear grade (15/21). Five-year locoregional recurrence-free survival (LRRFS) for all patients was 54%±12%, and 5-year overall survival (OS) was 51%±13%. The only statistically significant feature associated with LRRFS was the presence of a spindle cell component in the tumor. Patients with >10% spindle cell component had decreased LRRFS (log rank; P=0.006). The only statistically significant features associated with OS were patient age and tumor keratinization. Patients more than 60 years of age had decreased OS (log rank; P=0.035), and patients with tumors having at least focal keratinization had improved OS (log rank; P=0.027). Lymph node status, mitotic rate, tumor necrosis, cystic degeneration, clear cell change, and the presence of a pleomorphic component or associated ductal carcinoma in situ were not associated with either LRRFS or OS. In summary, primary SCC of the breast tends to be aggressive, particularly in patients more than 60 years of age and those with tumors having >10% spindle cell component. The presence of at least focal keratinization, however, is associated with significantly improved OS.

Myxofibrosarcoma of the Breast: Case Report

INTRODUCTION: Sarcomas of the breast account for less than 1% of all breast cancers. All of them share some clinical and pathological features. Myxofibrosarcoma is characterized by nodular growth, a mixoid matrix, a course, plexiform capillary pattern, and spindle or stellate tumor cells with hyperchromatic, atypical nuclei. Pathologic diagnosis is based on the overall morphology of the tumor and the exclusion of metaplastic carcinoma. This case report describes a mixofibrosarcoma of the breast in a young woman. CASE REPORT: A 26 year-old woman with two separate lumps in the left breast for the past three years. On clinical examination, there were two firm tumors measuring 5cm and 6 cm in the upper inner quadrant. There was no palpable ipsilateral axillary limph nodes. Ultrassonography showed low echogenic masses, a nonhomogeneous internal echo pattern, 4, 1 x 3, 9 cm and 3, 1 x 2, 3 cm in size. Core biopsy was performed twice and showed a myxoid lipomatous tumor. We performed a local excision which revealed a mesenchymal malignant tumor with myxoid and pleomorphic components. The immunohistochemestry (IHC) was negative for cytokeratin and S 100. The patient was submitted to simple mastectomy and the histopathological analyses confirmed the diagnosis of myxofibrosarcoma of the breast. DISCUSSION: Sarcomas of the breast are a heterogeneous group of tumors. The morphologic and clinical spectrum of each specific subtype of mammary sarcoma has been slow to emerge. IHC is a widely available diagnostic method in cases in which the morphology is ambiguous. Pathologic diagnosis of mammary myxofibrosarcoma is based on the overall morphology of the tumor and the exclusion of metaplastic carcinoma. There are no IHC markers for myxofibrosarcoma.

Sarcomatoid Carcinoma Arising from Mature Cystic Teratoma

Malignant transformation of mature cystic teratoma (MCT) is rare. Sarcomatoid carcinoma is a neoplasm comprising malignant mesenchymal cells and a conventional carcinomatous area. Here, we report a case of sarcomatoid carcinoma arising from an MCT in the left ovary of a 45-year-old woman. A unilocular cyst consistent with MCT but a nodule within the cyst was confirmed from the resected ovary. Microscopically, the nodule showed both squamous cell carcinoma and pleomorphic sarcomatous components admixing with each other. Lining epithelial cells at the periphery of the main tumor showed squamous metaplasia. It is important to find a squamous cell component, either benign or malignant, when a sarcomatous component was present in the ovary tumor.

Pleomorphic and dedifferentiated leiomyosarcoma: clinicopathologic and immunohistochemical study of 41 cases

In this article, we supplement the few published articles by describing the clinical and pathologic features of pleomorphic and dedifferentiated leiomyosarcoma from 41 patients (27 women and 14 men) with an age range of 25 to 75 years (mean, 56.5 years), representing the largest cohort reported to date. The typical leiomyosarcoma component accounted for <5% to 60% (mean, 15%) of the tumor. The pleomorphic sarcoma component was composed of polygonal cells in 57% of cases, spindle cells in 21%, a combination of polygonal, epithelioid, rhabdoid, and/or spindle cells in 18%, and predominantly epithelioid cells in 3%. The classical leiomyosarcoma component was positive for at least one myogenic immunohistochemical marker in 29 tumors tested; smooth muscle actin in 100% (27/27), calponin in 90% (9/10), muscle-specific actin in 90% (10/11), desmin in 86% (23/27), smooth muscle myosin heavy chain (SMMS-1) in 67% (4/6), and caldesmon in 57% (4/7). The pleomorphic sarcoma component was reactive for at least one muscle marker in 77% (23/30) of cases; smooth muscle actin in 63% (17/27), calponin in 60% (6/10), SMMS-1 in 60% (3/5), desmin in 59% (16/27), muscle-specific actin in 40% (4/10), and caldesmon in 29% (2/7). The classical leiomyosarcoma component was often strongly positive for myogenic markers, and the pleomorphic sarcoma component usually showed focal and less intense immunoreactivity. Based on staining for muscle markers in the pleomorphic component, twenty-three cases were designated as pleomorphic leiomyosarcoma, and 7 cases were designated as dedifferentiated leiomyosarcoma (negative for all muscle markers used). Eleven cases, in which tissue was not available for immunhistochemical stains, the question of pleomorphic versus dedifferentiated leiomyosarcoma could not be answered. The incidence of metastasis was 89% (32/36) and the mortality rate was 50% (18/36) at last follow-up (3-104 months; mean, 27.5 months).

Esophageal pleomorphic giant cell carcinoma combined with small cell carcinoma

Herein is presented the case of an esophageal pleomorphic giant cell carcinoma combined with small cell carcinoma (SCC). The patient, a 77-year-old man, initially presented with dysphagia and hoarseness, and endoscopy indicated a large esophageal tumor. Despite chemoradiation therapy, the patient died from widespread local extension of the tumor and distant metastases approximately 8 months after onset of the symptoms. Histologically, the primary tumor was composed of pleomorphic tumor components, SCC components, and a tiny focus of squamous cell carcinoma. The pleomorphic tumor cells, consisting of solid sheets of poorly cohesive epithelioid cells and numerous multinucleated giant cells with abundant eosinophilic cytoplasm, were immunohistochemically positive for vimentin and desmin, with scattered positivity for epithelial membrane antigen (EMA) and neuron-specific enolase (NSE), but negative for myoglobin. These findings were histopathologically compatible with pleomorphic giant cell carcinoma occurring at other sites such as the lung. SCC cells, morphologically similar to their pulmonary counterpart, were positive for EMA and some neuroendocrine markers such as chromogranin A and NSE, and occasionally positive for vimentin and desmin. Esophageal pleomorphic giant cell carcinoma can occur in close association with SCC, and should be included in the differential diagnosis of esophageal tumors showing pleomorphism.

Pleomorphic lobular carcinoma of the breast: role of comprehensive molecular pathology in characterization of an entity

Immunohistochemical analysis of E-cadherin has changed the way lobular neoplasia is perceived. It has helped to classify difficult cases of carcinoma in situ with indeterminate features and led to the identification of new variants of lobular carcinoma. Pleomorphic lobular carcinoma (PLC) and pleomorphic lobular carcinoma in situ (PLCIS), recently described variants of invasive and in situ classic lobular carcinoma, are reported to be associated with more aggressive clinical behaviour. Although PLC/PLCIS show morphological features of classic lobular neoplasia and lack E-cadherin expression, it is still unclear whether these lesions evolve through the same genetic pathway as lobular carcinomas or are high-grade ductal neoplasms that have lost E-cadherin. Here we have analysed a case of extensive PLCIS and invasive PLC associated with areas of E-cadherin-negative carcinoma in situ with indeterminate features, using immunohistochemistry, chromogenic in situ hybridization, high-resolution comparative genomic hybridization (CGH) and array-based CGH. We observed that all lesions lacked E-cadherin and beta-catenin and showed gain of 1q and loss of 16q, features that are typical of lobular carcinomas but are not seen in high-grade ductal lesions. In addition, amplifications of c-myc and HER2 were detected in the pleomorphic components, which may account for the high-grade features in this case and the reported aggressive clinical behaviour of these lesions. Taken together, these data suggest that at least some PLCs may evolve from the same precursor or through the same genetic pathway as classic lobular carcinomas.

Carcinome sarcomatoïde de l’œsophage : à propos d’un cas avec étude immunohistochimique et moléculaire

Sarcomatoïd carcinoma is a rare tumor of the esophagus, characterized macroscopically by a polypoid aspect and histologically by the association of spindle cell carcinoma with sarcomatous pleomorphic component. We report here a case of esophagus sarcomatoïd carcinoma. Diagnosis was based on immunohistochemical analysis of tIssue samples. Human papillomavirus (HVP) detection by PCR amplification of DNA extracted from tumoral tIssue was negative, ruling out the role of HPV infection in this tumor.

Clinical, Histopathologic, and Biologic Features of Pleomorphic Lobular (Ductal-Lobular) Carcinoma In Situ of the Breast: A Report of 24 Cases

We reviewed 10 cases of pleomorphic lobular (ductal lobular) carcinoma in situ (PL/DLCIS) of the breast and compared them with 14 cases of pleomorphic lobular carcinoma in situ (PLCIS) found in association with invasive pleomorphic lobular carcinoma. The histologic features; immunohistochemical staining for estrogen receptors (ERs), p53, Ki67, E-cadherin, and gross cystic disease fluid protein-15 (GCDFP-15); and results of fluorescence in situ hybridization for HER-2/neu gene amplification were evaluated in all 24 cases. Histologically, PL/DLCIS cells were similar to those of PLCIS with invasion in that they were discohesive and medium to large in size with moderate to marked nuclear pleomorphism, small to prominent nucleoli, and moderate to abundant eosinophilic or vacuolated cytoplasm. In both groups, central necrosis was present in a small number of cases, and classic LCIS coexisted with the in situ lesion in less than half of the cases; in situ carcinomas were positive for ERs in 23 (100%) of 23 cases, p53 in 6 (25%) of 24 cases, and GCDFP-15 in 14 (74%) of 19 cases. The percentage of Ki67-positive tumor nuclei indicated moderate to high (more than 20%) proliferative activity in 8 (47%) of 17 cases. Immunostaining for E-cadherin was negative in all 24 cases. HER-2/neu gene amplification was observed in 1 (4%) of 23 cases. In cases with associated invasion, PLCIS had cytologic features and immunostaining patterns similar to those of the invasive pleomorphic component. Seven of the 10 patients who had PL/DLCIS without invasion underwent lumpectomy or simple mastectomy. Six of these patients had no evidence of disease in follow-up periods ranging from 4 to 32 months; the seventh patient developed recurrent disease 12 months after undergoing lumpectomy. We conclude that the cytologic features and biomarker expression profile of PL/DLCIS are similar to those of PLCIS with invasion but somewhat different from those of classic LCIS and ductal carcinoma in situ. Long-term follow-up studies are needed to further define the natural history of PL/DLCIS and its optimal management.

Novel cell lines established from a human myxoid malignant fibrous histiocytoma arising in the uterus

Two cell lines (Nara-H and Nara-F) with different phenotypes were established from a myxoid MFH of the uterus. In vitro, Nara-F grew in sheets showing a storiform arrangement and Nara-H in raised colonies. Although tumors generated in nude mice shared similar morphological features of abundant myxoid tumor in Nara-H and -F, the pleomorphic component was conspicuous in Nara-F. Both cell lines produced hyaluronic-acid but CD44 was expressed only in Nara-H. Estrogen receptor α (ER α) and progesterone receptor (PgR) were detected in Nara-H. Nara-F was positive for ER β and PgR. Among hormonal agents, the response to the anti-estrogen tamoxifen was more sensitive than progesterone agents. This report illustrates the characteristics of these newly established cell lines, and presents the possibility of an adjuvant hormonal therapy for MFH.

Renal angiomyolipoma: a clinicopathologic, immunohistochemical, and follow-up study of 46 cases.

We reviewed 46 cases of renal angiomyolipoma covering the period from 1977 to 1997. Eight cases were associated with tuberous sclerosis and one with lymphangiomyomatosis. Histologically, the lesions were most often classic with the three usual components, i.e., mature adipose tissue, thick-walled blood vessels, and smooth muscle. Seven cases were particularly misleading: three cases were entirely adipose mimicking liposarcoma: two cases had an exclusively smooth-muscle component, one mimicking lymphangiomyomatosis and one with epithelioid cells; another case had a monophasic epithelioid pleomorphic component ("REON": renal epithelioid oxyphilic neoplasm) and proved to be fatal; and another case was associated with collecting duct carcinoma. The immunohistochemical profile showed the coexpression of alpha-smooth-muscle actin and HMB45. Our study is the first to show positivity of estrogen and progesteron receptors or both in more than 25% of cases. Of 35 cases with follow-up information, only one patient died of malignant spread of angiomyolipoma.

Adipose differentiation in cystosarcoma phyllodes. A study of 14 cases.

Adipose differentiation is an uncommon stromal alteration in cystosarcoma phyllodes (CP). We have studied 14 lesions to define the structural variation and prognostic significance of these rare forms of CP. All patients were women between 17 and 71 years of age (mean 40 years; median 42 years). Most were first seen with a mass; three were pregnant. Grossly, the lesions were circumscribed with lobulated cut surfaces. Microscopically, the mesenchymal component showed adipose differentiation that ranged from mature fat to liposarcoma with well-differentiated, myxoid, or pleomorphic components. Six lesions were high-grade malignant CP with immature cellular mesenchyme, abundant mitoses, and areas of pleomorphic liposarcoma. Seven tumors were low-grade malignant CP with few mitoses, relatively low cellularity, and myxoliposarcoma. One tumor with slight periductal condensation and mature adipose tissue was a benign CP, which we named lipophyllodes tumor. Two patients had concurrent breast carcinoma, and two others subsequently had carcinoma. The follow-up was 8-90 months (mean 46 months; median 39 months). There was one recurrence among eight patients treated with simple excision and no recurrences in six treated with mastectomy. One woman died of metastatic breast carcinoma. All others are alive and free of disease. CP with adipose differentiation can be graded histologically on the basis of this component. Despite the high-grade histology in some instances, the patients had an excellent prognosis when the tumors were completely excised.

LIPOSARCOMA

Fifty‐two cases of liposarcoma were analyzed clinicopathologically, and were grouped into the following five types: myxoid (28 cases), well‐differentiated (14 cases), pleomorphic (4 cases), round‐cell (3 cases), and mixed (3 cases). Three of the 28 myxoid tumors showed a pleomorphic pattern resembling that of the myxoid variant of malignant fibrous histiocytoma, and one of the 3 round‐cell tumors was considered to be a malignant counterpart of hibernoma. Ages ranged from 22 to 86 years with the average age of 49 years, the average patients with myxoid or round‐cell liposarcoma being over 10 years younger than those with well‐differentiated or pleomorphic liposarcoma. There was also a variation in the site of predilection of the cases: the great majority of myxoid type tumors occurred in the thigh, popliteal fossa and buttock (23 cases), while the majority of well‐differentiated type tumors were seen in the retroperitoneum (10 cases). The rate of local recurrence of the tumor was 46%. Four of the 5 well‐differentiated liposarcomas which recurred exhibited dedifferentiated pleomorphic components resembling those in malignant fibrous histiocytoma. The prognosis was more favorable in patients with ordinary myxoid tumors than in those with well‐differentiated tumors. The overall relative five‐year survival rate was 63%.