Myxoid variant of epithelioid leiomyosarcoma of the uterus.

A rare case of myxoid variant of epithelioid leiomyosarcoma of the uterus in a 76-year-old woman is reported. Palpation and computed tomography revealed an enlarged uterus. Total hysterectomy and bilateral salpingo-oophorectomy were performed, and a hemispheric tumor, measuring 2.7 x 2.5 x 1.8 cm, was found protruding into the uterine cavity of the upper uterine segment. The tumor contained a prominent myxoid stroma and epithelioid tumor cells, which were round and polygonal in shape and showed positive immunoreactivity for desmin and vimentin. High mitotic activity was observed in the tumor cells. Electron microscopic examination revealed bundles of filaments in the cytoplasm and fine reticular material in the extracellular matrix. Histochemically, the myxoid stroma contained abundant acid mucopolysaccharide. The tumor cells were considered to originate from smooth muscle cells, while the myxoid stroma expressed varying differentiation of uterine mesenchymal cells. The patient is currently well with no evidence of recurrence or metastasis one year after the operation.     

GASTRIC LEIOMYOSARCOMA WITH MASSIVE MYXOID DEGENERATION: A Histochemical and Ultrastructural Study

Histochemical and ultrastructural features of a gastric myxoid leiomyosarcoma from a 55-year-old man were examined. At autopsy, the tumor was located mainly in the greater omentum and was directly connected to a coinsized gastric tumor. Multiple hepatic metastases and peritoneal disseminations were noted. Light-microscopically, the tumor was composed of a prominent myxoid stroma and ovoid or rounded tumor cells. The myxoid stroma was stained weakly basophilic with hematoxylin and eosin, and was mainly composed of hyaluronic acid. Tumor cells in the stomach were spindle-shaped and apparently myogenic. Ultrastructurally, the gastric tumor cells showed a loose cohesion with junctional apparatuses, pinocytotic vesicles, basal laminae, and cytoplasmic filaments with focal densities. Tumor cells in the omentum and the liver, however, were poorly differentiated and showed an epithelioid nature in part. This unique leiomyosarcoma is reported with some differential diagnoses from other myxoid sarcomas.     

Gastric leiomyosarcoma with massive myxoid degeneration. A histochemical and ultrastructural study

Histochemical and ultrastructural features of a gastric myxoid leiomyosarcoma from a 55-year-old man were examined. At autopsy, the tumor was located mainly in the greater omentum and was directly connected to a coinsized gastric tumor. Multiple hepatic metastases and peritoneal disseminations were noted. Light-microscopically, the tumor was composed of a prominent myxoid stroma and ovoid or rounded tumor cells. The myxoid stroma was stained weakly basophilic with hematoxylin and eosin, and was mainly composed of hyaluronic acid. Tumor cells in the stomach were spindle-shaped and apparently myogenic. Ultrastructurally, the gastric tumor cells showed a loose cohesion with junctional apparatuses, pinocytotic vesicles, basal laminae, and cytoplasmic filaments with focal densities. Tumor cells in the omentum and the liver, however, were poorly differentiated and showed an epithelioid nature in part. This unique leiomyosarcoma is reported with some differential diagnoses from other myxoid sarcomas.     

Myxoid Variant of Epithelioid Leiomyosarcoma of the Uterus

A rare case of myxoid variant of epithelioid leiomyosarcoma of the uterus in a 76-year-old woman is reported. Palpation and computed tomography revealed an enlarged uterus. Total hysterectomy and bilateral salpingo-oophorectomy were performed, and a hemispheric tumor, measuring 2.7 X 2.5 X 1.8 cm, was found protruding into the uterine cavity of the upper uterine segment. The tumor contained a prominent myxoid stroma and epithelioid tumor cells, which were round and polygonal in shape and showed positive immunoreactivity for desmin and vimentin. High mitotic activity was observed in the tumor cells. Electron microscopic examination revealed bundles of filaments in the cytoplasm and fine reticular material in the extracellular matrix. Histochemically, the myxoid stroma contained abundant acid mucopolysaccharide. The tumor cells were considered to originate from smooth muscle cells, while the myxoid stroma expressed varying differentiation of uterine mesenchymal cells. The patient is currently well with no evidence of recurrence or metastasis one year after the operation. Acta Pathol Jpn 41: 778-783, 1991.     

Inflammatory myofibroblastic tumor of the uterus with prominent myxoid change

A surgical case of inflammatory myofibroblastic tumor arising in the uterine corpus and exhibiting prominent myxoid change of the stroma is reported. The patient was a 63-year-old woman with a large tumor mass that filled the uterine cavity and measured 11 cm in maximal dimension. The tumor had a gelatinous appearance and consisted of a loose proliferation of stellate or polygonal cells on a myxomatous background. Fascicular proliferation of spindle cells was also observed focally, and a chronic inflammatory cell infiltration was seen in many areas. Tumor cells had mild atypism and were immunoreactive for vimentin, alpha-smooth muscle actin, and anaplastic lymphoma kinase (ALK). Focal immunoreactivity for high-molecular-weight caldesmon (h-caldesmon) was also noted. The patient has been free from recurrence for 8 months. Inflammatory myofibroblastic tumor of the uterus occasionally shows prominent myxoid change of the stroma, and differentiation from myxoid leiomyosarcoma is problematic in these cases. Based on the immunoreactivity of tumor cells for ALK and h-caldesmon, the present tumor was considered inflammatory myofibroblastic tumor showing a focal phenotypic transition from myofibroblasts to smooth muscle cells.     

Ultrastructural immunolocalization of a cartilage-specific proteoglycan,aggrecan, in salivary pleomorphic adenomas

A pleomorphic adenoma (PA) is the most common epithelial tumor in the salivary glands, but it frequently shows a mesenchyme-like histology, including the presence of myxoid and chondroid areas. Cartilage-specific matrix proteins are deposited in PA. Aggrecan is a major component of cartilage-specific proteoglycans. The present study examined the ultrastructure of the stromal areas in ten salivary PA specimens and investigated the distribution of aggrecan by immunoelectron microscopy. Aggrecan was deposited in the myxoid and chondroid stroma of PA. Ultrastructural observations revealed many proteoglycan cores and fibrils in the myxoid stroma and some spindle-shaped neoplastic myoepithelial cells with vacuoles and actin filaments in the myxoid areas. By immunoelectron microscopy, positivity for aggrecan was observed in the vacuoles of neoplastic myoepithelial cells, which coexisted with the viscous materials, and it was also frequently seen in electron-dense crystals in the myxoid stroma. These findings suggest that neoplastic myoepithelial cells produce aggrecan and release it from vacuoles, and aggrecan is then deposited in the myxoid stroma. Aggrecan deposition is therefore considered to play an important role in the formation of the mesenchyme-like stroma, especially the myxoid stroma.     

Extraskeletal myxoid chondrosarcoma of the nasopharynx

Extraskeletal myxoid chondrosarcoma is a rare but distinct entity with special clinicopathological, immunohistochemical, cytogenetical and outcome features. This tumor developed from soft tissues. A few cases have been reported in the head and neck in the literature. We report two new cases of extraskeletal myxoid chrondrosarcoma presenting in such an unusual site: one involved the left nasal cavity of a 67-year-old man and the second the sphenoidal sinus of a 71-year-old woman. The microscopic examination revealed nests of round small cells dispersed in a myxoid stroma. The myxoid material was stained with Alcian Blue with and without hyaluronidase application whereas no PAS staining was observed. The immunohistochemical staining showed reactivity with S-100 protein and vimentin in two cases and with EMA in one case. These results allowed us to exclude other differential diagnoses: soft tissue tumors with a myxoid stroma (myxoma, myxoid liposarcoma and myxofibrosarcoma). No staining with anti-KL1 allowed us to exclude chordoma. Curative surgery was not possible. Both patients were given radiotherapy and the tumor regressed in one.     

Myxoid endometrial stromal sarcoma of the uterus

A rare case of a myxoid type of endometrial stromal sarcoma of the uterus in a 41-year-old woman is reported. A tumor was found in the myometrium and was well circumscribed, measuring 9 x 7 x 7 cm in size. The tumor was mainly composed of a hypocellular area with tumor cells separated by prominent myxoid stroma. The tumor cells were spindle-shaped and resembled endometrial stromal cells. Numerous small thin-walled vessels were seen throughout the tumor. Immunohistochemically, the tumor cells were diffusely stained for estrogen and progesterone receptors and CD10, and focally and weakly for HHF35, alpha-smooth muscle actin and desmin, but not stained for h-caldesmon. These results indicated that the tumor originated from endometrial stromal cells. The tumor had an increased mitotic activity (MIB-1 labeling index: 1-10%), and focally showed nuclear pleomorphism. Thus, this tumor had a malignant potential and was diagnosed as a myxoid type of low-grade endometrial stromal sarcoma. The patient is currently well with no evidence of local recurrence or metastasis 21 months after the operation. This case indicates a wide morphological spectrum of endometrial stromal tumor. A myxoid endometrial stromal sarcoma should be considered in the different diagnosis of the intramural myxoid tumors in the uterus.     

Clear CelI HepatocelIular Caxinoma with Abundant Myxoid Stroma

A case of the clear cell variant of hepatocellular carcinoma with an abundant myxoid stroma is presented. The tumor occurred in a 55 year old Japanese man, and swelling of the scrotum was the initial symptom. The patient underwent high-level orchiectomy, and the pathologic diagnosis was a metastatic tumor on the surface of the processus vaginalis and intact testis. Extensive examination failed to show a primary site. Subsequent autopsy revealed a large hepatic tumor and metastatic nodules with a prominent myxoid appearance in multiple organs. Histological-ly, each tumor consisted of uniform small tumor cells with clear cytoplasm attributed to abundant accumulation of glycogen particles, and an abundant myxoid stroma was also present. The tumor cells were positive for keratin, α1– antitrypsin, α1-antichymotrypsin, liver ferritin, prealbumin, and fibrinogen, but lacked α fetoprotein. These findings indicated that this case was hepatocellular carcinoma of the clear cell type with a prominent myxoid stroma. Acta Pathol Jpn 42: 897–903, 1992.     

Bilateral fibroepithelial polypi of labium minus with atypical stromal cells.

A case of fibroepithelial polyp of labium minus with stromal atypia is described. This unusual tumor has only recently been reported occurring in the vulva. The tumor measured 12 cm in maximal diameter and its cut surface was soft and myxoid. After fixation the tumor was considerably smaller in size. The light microscopic findings were of a loose acellular myxoid stroma, traversed by thin walled dilated vascular spaces and covered by stratified squamous epithelium and with sparse fibroblast-like cells dispersed throughout. This case is unusual as fibroepithelial polyps with stromal atypia are an uncommon tumor of the vulva, are rarely bilateral and in this site no lesion previously has exceeded 4.0 cm in diameter.     

Clear cell hepatocellular carcinoma with abundant myxoid stroma.

A case of the clear cell variant of hepatocellular carcinoma with an abundant myxoid stroma is presented. The tumor occurred in a 55-year-old Japanese man, and swelling of the scrotum was the initial symptom. The patient underwent high-level orchiectomy, and the pathologic diagnosis was a metastatic tumor on the surface of the processus vaginalis and intact testis. Extensive examination failed to show a primary site. Subsequent autopsy revealed a large hepatic tumor and metastatic nodules with a prominent myxoid appearance in multiple organs. Histologically, each tumor consisted of uniform small tumor cells with clear cytoplasm attributed to abundant accumulation of glycogen particles, and an abundant myxoid stroma was also present. The tumor cells were positive for keratin, alpha 1-antitrypsin, alpha 1-antichymotrypsin, liver ferritin, prealbumin, and fibrinogen, but lacked alpha-fetoprotein. These findings indicated that this case was hepatocellular carcinoma of the clear cell type with a prominent myxoid stroma.     

Fine needle aspiration of malignant melanoma with myxoid features: A case report with molecular analysis

Malignant melanoma with myxoid features (MMM) is a rare melanoma variant in which tumor cells are embedded within a basophilic myxoid stroma. The stromal matrix is composed of acidic mucopolysaccharides, which are thought to be produced by mesenchymal stromal cells in response to melanoma invasion. Interestingly, this myxoid matrix is more often seen in metastasis from a primary tumor that does not have a myxoid stroma. The diagnosis of MMM on fine needle aspiration (FNA) can be confused with other myxoid tumors. Herein, we present a case of MMM diagnosed by FNA of a peri‐auricular lymph node in an 89‐year‐old man with a history of resected malignant melanoma. We describe the clinical, cytohistological, and immunohistochemical findings, and present the unique molecular alterations that were identified. We also discuss the differential diagnosis and potential diagnostic pitfalls associated with MMM.     

Myxoid dermatofibroma on a great toe: a case report

Dermatofibroma is a common benign fibrohistiocytic tumor with many clinicopathological variants. Myxoid dermatofibroma is one of these variants, which is characterized by marked stromal mucin deposition. This report presents a case of myxoid dermatofibroma on a great toe that had been slowly growing for two years. Histopathologically, the relatively well-circumscribed dermal tumor was separated from the epidermis by a small grenz zone. The tumor tissue consisted of oval to spindle-shaped cells with well-defined cell borders and spindly condensed nuclei. No cytologic atypia or mitotic figures were found. Although most of the tumor cells were embedded in a prominently myxoid stroma, typical features of classic dermatofibroma including a storiform growth pattern and more densely packed collagen were observed at the periphery. Immunohistochemically, the tumor cells showed positive staining for CD68 and CD99, and negative staining for CD34 and S-100. Histopathological differential diagnoses of myxoid dermatofibroma include soft tissue neoplasms with myxoid tumor stroma, such as superficial acral fibromyxoma, cellular digital fibroma, superficial angiomyxoma, myxoid dermatofibrosarcoma protuberans and low-grade fibromyxoid sarcoma. Immunohistochemical staining can be useful in the differential diagnosis of these tumors. This case highlights the challenges encountered in the histopathological interpretation of myxoid dermatofibroma. Pathologists should keep in mind the diagnosis of myxoid dermatofibroma when dealing with myxoid neoplastic lesions arising on acral sites.     

Myxoid melanoma of the skin

We report a case of cutaneous myxoid melanoma in a 61-year-old man. Histologically, the tumor, which showed an adjacent intraepidermal proliferation of atypical melanocytes, was composed of spindle-shaped and epithelioid cells with atypical nuclei, arranged in lobules and embedded in a prominent myxoid stroma. Primary cutaneous myxoid melanoma is rare: we found only one other example in the literature.     

An undifferentiated sarcoma in a rat resembling extraskeletal myxoid chondrosarcoma in man

A soft tissue tumor occurring in the inguinal subcutaneous tissue was detected in a 109-week-old male F344 rat. Macroscopically, the tumor mass showed no skeletal relationship and a gelatinous multinodular appearance. Histologically, the tumor consisted of irregular lobules separated by scant fibrous septa. In each lobule, tumor cells were arranged in cords and strands in the plentiful myxoid stroma. The tumor cells showed marked pleomorphism, and had large, round to ovoid nuclei and abundant eosinophilic cytoplasm. Mitotic figures were often seen. Myxoid stroma of the tumor contained a large amount of acid mucopolysaccharides and collagen type II, which were demonstrated by histochemistry and immunohistochemistry respectively. The tumor cells showed positive immunoreactivities for vimentin and S100 protein. Ultrastructural examination revealed that the tumor cells had a large amount of mitochondria, Golgi complex and dilated rough endoplasmic reticulum containing amorphous material, and the myxoid stroma contained collagenous fibrils and proteoglycan particles. Based on these results, the present tumor in a rat resembled extraskeletal myxoid chondrosarcoma in man.     

Myxoid epithelioid gastrointestinal stromal tumor harboring an unreported PDGFRA mutation: report of a case and review of the literature

Activating mutations of platelet-derived growth factor receptor α (PDGFRA) are detected in a significant proportion of gastrointestinal stromal tumors (GISTs), in addition to the more frequent mutation in c-kit. GISTs with PDGFRA mutations have been found to have several characteristic morphological features, sometimes allowing to discriminate them from GISTs with c-kit mutations. Among these, epithelioid morphology in tumor cells and tumor-infiltrating mast cells are powerful predictors of PDGFRA mutations. Although myxoid stroma by itself is not so much a reliable predictor of PDGFRA mutation, myxoid stroma in conjunction with epithelioid morphology in tumor cells is a powerful predictor of mutations in this gene. GISTs showing either weak or negative immunoreactivity for c-kit and epithelioid cells with myxoid stroma are called myxoid epithelioid GISTs, which typically show PDGFRA mutation. Herein, we presented a case of a 59-year-old woman with myxoid epithelioid GIST of the stomach. A unique finding in this case was eosinophil infiltration, probably more numerous than mast cells; mast cell infiltration is known to be usually found in myxoid epithelioid GIST. The existence of a similar mechanism in eosinophil and mast cell recruitment via tumor-producing stem cell factor is speculated. Mutational analyses revealed a PDGFRA exon 18 mutation: D842_H845del, D846N. Combined deletion and substitution mutation has been reported in rare instances, but to the best of our knowledge, D846N has not been documented.     

Myxoid leiomyoma of the vulva mimicking aggressive angiomyxoma

A case of vulvar leiomyoma with extensive myxoid change in a 40 year old female is described. The tumor had a unique connection with a non-degenerative leiomyoma that compressed the rectum and the bladder. Scattered smooth muscle cells in a loose myxoid stroma were immunoreactive for desmin. Fibroblast-like spindle cells were immunoreactive for vimentin but not for desmin. The initial, although incorrect, pathological diagnosis of the tumor was aggressive angiomyxoma based on the similarity in both clinical and pathological aspects with this more invasive tumor. Myxoid vulvar leiomyoma should also be differentiated from angio-myoflbroblastoma. The key to the differential diagnosis is the presence of interlacing smooth muscle cells and an awareness of tendency toward myxoid change in vulvar leiomyomas.     

A Parathyroid Myxoadenoma Observed Grossly

We are reporting a case of a patient with primary hyperparathyroidism because of an unusual parathyroid adenoma. The tumor had an extensive myxofibrous stroma without an identifiable lipomatous component. Though moderate to extensive myxoid alteration of the stroma has been reported in lipoadenomas, to the best of our knowledge, this is the first parathyroid adenoma in which the myxomatous component was recognized grossly and which lacked a stromal adipose component.     

Basal cell adenocarcinoma arising from the minor salivary gland in the soft palate: a case report

Basal cell adenocarcinomas (BCACs) of the oral minor salivary gland are very rare neoplasms. We report on an 86-year-old woman with BCAC arising from the minor salivary gland in the soft palate. Histologically, the tumor was located in the submucosa and showed microinvasion into the adjacent soft tissue without encapsulation. It contained tiny tumor islands with solid and tubular patterns, as well as myxoid stroma. The neoplastic cells were basaloid cells and were composed of large pale cells and small dark cells. They were positive for alpha-smooth muscle actin, cytokeratin 14, and vimentin in the periphery of the tumor island, showing a myoepithelial differentiation. The myxoid stroma was positive for alcian blue and colloidal iron. Apical membranes of the neoplastic cells were positive for MUC1 and CEA. The present case is the 14th documented case of oral BCAC (the fifth case of palatal BCAC).