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The patient was a 54-year-old woman, who died of chronic cardiac insufficiency after a clinical course of 2 years and 4 months. She had complained of myalgia, muscle weakness, and blepharoptosis before the onset of cardiac symptoms, but there was no evidence of myasthenia gravis or collagen-vascular diseases. At autopsy, the heart (280 g) showed marked dilatation of the four chambers and thinning of the ventricular walls. Diffuse and intense lymphocytic infiltration and extensive fibrosis were noted, with the latter being accentuated in the subendocardial and subepicardial zones. Small foci of myocardial necrosis were scattered and a small number of multinucleated giant cells were found, but epithelioid cell granulomas, Aschoff's nodules, and viral inclusion bodies were not observed. Some cardiomyocytes showed the aberrant expression of the HLA-DR antigen. No viral genomes were detected in myocardial tissue using a multivirus real-time polymerase chain reaction. The protracted clinical course, presence of active inflammatory changes at autopsy, expression of the HLA-DR antigen on cardiomyocytes, and absence of viral genomes in myocardial tissue suggest that autoimmune mechanisms played an important role in the pathogenesis and persistence of myocarditis in this patient., (© 2017 Japanese Society of Pathology and John Wiley & Sons Australia, Ltd.)

We report a case of ductulo-insular pancreatic endocrine tumor (DI-PET) in a 50-year-old woman. The patient presented with symptoms and signs of hypoglycemia, and a small tumor in the uncus of the pancreas was extirpated. The tumor predominantly consisted of a neuroendocrine tumor (NET) of grade 2, which surrounded a minor component of ductular proliferation accompanied by a desmoplastic stroma. Both components were largely juxtaposed but admixed with each other in small areas. The NET component was immunoreactive for insulin and accompanied by the marked deposition of amyloid in the stroma. The ductular component consisted of a haphazard proliferation of ductules showing mildly atypical cytological features and immunoreactivities for cytokeratins 7 and 19. DI-PET is a rare composite neoplasm that should be distinguished from mixed ductal-neuroendocrine carcinoma because of the marked differences in treatment modalities and prognoses between the tumors. DI-PET associated with stromal amyloid deposition has not been reported to date. The 'transdifferentiation' of NET cells into ductular cells is considered as the most plausible histogenetic mechanism of this tumor, although other possibilities, such as an origin from a primitive endodermal stem cell or the induction of ductular proliferation by stimulation with NET-derived humoral factors, cannot be excluded., (© 2015 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd.)

A rare case of a mixed endometrial stromal and smooth muscle tumor arising in the uterus of a 74-year-old woman is reported. The patient underwent hysterectomy for an enlarging uterine mass, and a large intramural tumor, showing marked central hyaline necrosis with calcification, was found. The tumor consisted of an admixture of a low-grade endometrial stromal sarcoma (ESS) and a fascicular proliferation of spindle cells suggesting smooth muscle differentiation, and a characteristic 'star-burst' appearance was found. In the ESS region, there were a few small foci of anaplasia where large polygonal cells with atypical nuclei and abundant eosinophilic cytoplasm proliferated, and the proliferative activity was locally increased in these foci. A small metastatic nodule appeared in the lung nine months after the hysterectomy, and the resected metastatic lesion showed features of anaplastic spindle cell sarcoma which was immunoreactive for CD10 but not for smooth muscle markers. Mixed endometrial stromal and smooth muscle tumors should be regarded as malignant neoplasms with the potential for hematogenous metastasis, particularly when they contain foci of cellular anaplasia., (© 2013 The Authors. Pathology International © 2013 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd.)

An extremely rare case of mixed adenoneuroendocrine carcinoma (MANEC) of the gallbladder is reported, in which the tumor showed diverse differentiation toward neuroendocrine tumor (grade 2), tubular adenocarcinoma, squamous cell carcinoma, and, in addition, osteosarcoma. The patient was an 80-year-old man, who underwent cholecystectomy because of a large polypoid tumor filling the gallbladder lumen. The tumor consisted of an intimate admixture of neuroendocrine tumor (grade 2) and tubular adenocarcinoma, and, in many areas, cell nests of neuroendocrine tumor appeared to bud off from tubular structures of the adenocarcinoma, in a manner resembling the 'ductulo-insular complex' seen in nesidioblastosis of the pancreas. Small areas of squamous cell carcinoma were also found. The stroma consisted of a dense proliferation of atypical spindle cells showing focal osteosarcomatous differentiation, and an apparent transition from an epithelial tissue component to atypical spindle cells was observed. Immunohistochemically, neuroendocrine cells were positive for synaptophysin, chromogranin A, and serotonin, and the sarcomatoid stroma was partly immunoreactive for cytokeratin. The present case is the first example of MANEC of the gallbladder with simultaneous squamous cell carcinomatous and osteosarcomatous differentiation. 'Neometaplasia' of carcinoma cells in diverse directions was considered the most plausible explanation for the formation of this multifaceted neoplasm., (© 2013 The Authors. Pathology International © 2013 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd.)

Reported here is a case of Müllerian adenosarcoma of the ovary which contained a primitive neuroectodermal tissue component within the stroma. The adenosarcoma coexisted with clear cell adenocarcinoma in an endometriotic cyst. The patient was a 33-year-old woman with a large unilocular endometriotic cyst of the right ovary. On the internal wall of the cyst, both a plaque-like protrusion with a papillary surface and a dome-like mural nodule were noted. The former exhibited features of Müllerian adenosarcoma, and the latter showed those of clear cell adenocarcinoma. In the deeper portion of adenosarcoma, teratoma-like tissue which contained various tissue components including primitive neuroectodermal tissue was found. The presence of primitive neuroectodermal tissue in the stroma of adenosarcoma suggested the diagnosis of 'adenosarcoma with neuroectodermal differentiation' ('teratoid adenosarcoma'), although the possibility of the incidental occurrence of an immature teratoma could not be completely excluded., (© 2011 The Authors. Pathology International © 2011 Japanese Society of Pathology and Blackwell Publishing Asia Pty Ltd.)

A case of colloid carcinoma (gelatinous carcinoma) of the intestinal type in the uterine cervix is reported along with the findings of an immunohistochemical study of intracytoplasmic mucus of the neoplastic cells. The patient was a 69-year-old woman with a circumferential uterine cervical tumor measuring about 4 cm. Histopathological examination of the hysterectomy specimen demonstrated typical features of colloid carcinoma. The tumor consisted of numerous mucous nodules, and low-columnar or cuboidal cells with intracytoplasmic mucus lined the margins of the mucous nodules or floated within them. The cytoplasm of neoplastic cells was immunoreactive for both cytokeratins 7 and 20, and the intracytoplasmic mucus was immunoreactive for MUC2 but negative for MUC5AC and MUC6. Nuclei of tumor cells were immunoreactive for CDX2. Colloid carcinoma is a very rare variant of mucus-producing adenocarcinoma of the uterine cervix and probably a heterogeneous group that consists of neoplasms of different histogeneses, that is, neoplasms of endocervical, gastric, and intestinal origins. Results of the immunohistochemical studies in the present case showed that neoplastic cells produced mucus of the large intestine type, thus verifying the presence of a distinct subtype of colloid carcinoma of the cervix that shows the intestinal phenotype.

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.

A case of serous cystadenocarcinoma of the pancreas in an 85-year-old woman is reported. The tumor extensively involved the body and tail of the pancreas and contiguously invaded the spleen. The histopathology of the tumor was similar to that of serous cystadenoma, but mild nuclear hyperchromatism and atypism were noted, and the neoplastic invasion of nerve fibers in the stroma was observed. In the spleen neoplastic cells forming microcysts were diffusely insinuated in the red pulp without the fibrous stroma. The patient is in good health without recurrence and metastasis after the operation. The present case is the second example of this kind of neoplasm that showed direct splenic invasion. Because serous cystadenocarcinoma of the pancreas exhibits bland cytological features, diligent search for the invasion of the surrounding tissue or peripheral nerves is needed for the differentiation from its benign counterpart.

A surgical case of proliferative funiculitis (pseudosarcomatous myofibroblastic proliferation of the spermatic cord) with a prominent mast cell infiltration is reported. A 67-year-old man with a history of right inguinal herniorrhaphy 7 years earlier was operated on for diffuse swelling of the inguinal region and scrotum. A large lipoma was found in the inguinal region, and a nodular lesion, measuring 2.7 cm in maximal dimension, was firmly attached to the right spermatic cord. The nodular lesion showed diffuse proliferation of fibroblasts and myofibroblasts associated with the deposition of collagen. A diffuse infiltration of numerous mast cells was found throughout the lesion. Lesions that belong to the group of inflammatory pseudotumors are rarely accompanied by a prominent mast cell infiltration, and the differentiation from mast cell neoplasms is often problematic in such cases. The present case is the first example of proliferative funiculitis associated with this rare phenomenon.

An unusual case of malignant peripheral nerve sheath tumor (MPNST) arising in the posterior mediastinum of a 59-year-old man is reported. Histopathologically, the tumor showed an admixture of a dense proliferation of small round cells resembling a primitive neuroectodermal tumor (PNET) and a pleomorphic spindle cell sarcomatous area. Abortive rosettes, primitive neural tube-like structures, and a few glandular structures were found in the small round cell area. Small round cells were immunoreactive for neural cell adhesion molecule and synaptophysin, but were not immunoreactive for MIC2 and neuron-specific enolase. Pleomorphic spindle cells were occasionally arranged in a storiform pattern and were diffusely immunoreactive for S-100 protein. The MPNST of small round cell type is distinguishable from PNET by its negative immunoreactivity for MIC2, and the present tumor is assumed to be derived from primitive neuroectodermal cells in the peripheral nerve capable of bidirectional (neuron and Schwann cell) differentiation.

A case of angiomyofibroblastoma-like tumor (lipomatous variant) that arose in the subcutis of the inguinal region of a 45-year-old man is presented. The maximum dimension of the tumor measured 39 mm and it was well circumscribed. Histopathological examination revealed a close admixture of plump spindle or stellate cells and mature adipocytes. These were arranged haphazardly or formed interconnecting thin cellular trabeculae on the myxoid or edematous background. The tumor was highly vascularized and contained a moderate amount of collagen fibers. Immunohistochemically, the tumor cells were positive for vimentin, CD34 and the estrogen receptor, but negative for alpha-smooth muscle actin and desmin. The differential diagnosis between the lipomatous variant of angiomyofibroblastoma and cellular angiofibroma or spindle cell lipoma is discussed, and the pathogenetic hypotheses about the occurrence of mature adipocytes within benign fibroblastic or myofibroblastic neoplasms are mentioned briefly. It is important for surgical pathologists to be acquainted with the occasional presence of adipocytes in these neoplasms to avoid misinterpretation.

A case of apocrine adenocarcinoma of the eyelid that showed unusually aggressive biological behavior is reported. The patient was a 57-year-old man who complained of discomfort and excessive lacrimation of the left eye. A subcutaneous tumor measuring 2.5 cm was found at the medial canthus of the upper eyelid, and a plica-like subconjunctival spread was noted in the lacrimal caruncle. Invasion into the extraocular muscles and metastasis to the cervical lymph nodes and bone were already present at the time of initial presentation. Histopathologically, the tumor showed features of poorly differentiated adenocarcinoma, and polygonal tumor cells had large, hyperchromatic nuclei with prominent nucleoli and abundant eosinophilic cytoplasm. The formation of ductal structures was found occasionally. The differentiation of the tumor cells towards the apocrine gland was corroborated by immunohistochemistry using monoclonal antibodies GCDFP-15 and B72.3. The histogenesis and pathological differential diagnosis are discussed briefly, and the tumor was considered to have originated in the Moll's gland in the eyelid. This case emphasizes that apocrine adenocarcinomas of the ocular region have the potential for aggressive biological behavior, including distant metastasis.