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Intestinal spirochetosis (IS) in humans is characterized by spirochetal microorganisms attached to the luminal surface of the colonic epithelium. In the present case, attached organisms appeared as 3- to 4 μm-thick (average thickness, 3.4 μm) basophilic fringes or haze in HE-stained endoscopic biopsy specimens. The basophilic fringes were clearly labeled by Treponema pallidum antiserum. Because IS is relatively rare in developed countries, thin basophilic fringes characteristic of IS are readily overlooked. Thus, the recognition of histological characteristics of this disease is important for its diagnosis.

A 38-year-old primiparous mother (gravida 1, para 0) at 27 weeks and 6 days' gestation reported that fetal movements had been absent for 6 days. All serological markers for infection were negative. Chorionic villus sampling at stillbirth delivery revealed trisomy 21 (47, XX, +21), indicative of Down syndrome. The macerated baby was female and weighed 1,290 g. There was no evidence of hydrops fetalis. Proliferating blast cells expressing megakaryoblastic/megakaryocytic antigen CD61 were mainly seen within the vessels, and some cells infiltrated outside of the vessels in almost all organs. Vessels of the umbilical cord and chorionic villi were filled with proliferating blast cells, but the blast cells were not apparent in the bone marrow. The diagnosis of transient abnormal myelopoiesis in Down syndrome was made. Hepatomegaly (64.5 g) was due to congestion and infiltration of CD61-positive blast cells within the vascular lumina and expanding outside the lumina accompanied by fibrotic change. The cause of death was attributed to liver insufficiency caused by liver fibrosis. An umbilical cord and chorionic villi examination may be helpful in the diagnosis of transient abnormal myelopoiesis when post-mortem examination is not permitted.

Multifocal adenomatous oncocytic hyperplasia (MAOH) is a non-neoplastic lesion that is classified as oncocytosis. MAOH is a rare entity of the parotid gland and accounts for approximately 0.1% of salivary gland lesions. Here, we report a case of MAOH of the parotid gland. The patient was a 71-year-old woman who presented with discomfort at the left side of her neck. Fine-needle aspiration cytology of the parotid gland revealed a loose sheet-like cluster of round to polygonal cells with granular cytoplasm against a hemorrhagic background. The cells had round to oval, centrally located nuclei with granular chromatin and without distinct nucleoli. Histologically, the lesion was formed of many variable-sized nodules, comprising oncocyte-like cells with small round nuclei and eosinophilic granular cytoplasm that was positive for mitochondrial antibodies. The diagnosis of MAOH is difficult to make by cytology alone, because the findings overlap with those of other oncocytic lesions. In particular, the cytological findings of MAOH have not been sufficiently reported to date. A correlation of cytology and histology was expected.

Basal cell carcinoma (BCC) is a slow-growing and frequently occurring tumor of the eyelids. Among BCC cases, there is a subtype of aggressive cases called horrifying BCC (HBCC). There are also rare BCC cases that show neuroendocrine differentiation. Here, we describe a case of HBCC with neuroendocrine differentiation. The patient, a 41-year-old woman, presented with abnormal left eye tearing and left cheek pain. On computed tomography imaging, a tumor that extended to the left orbit was detected in the left cheek. On cytological examination of fine-needle aspiration (FNA) samples, the tumor cells were observed as sheet-like clusters and single bare nuclei with a clear background; peripheral palisading was not clearly seen. On examination of the biopsy specimen taken after FNA, the tumor was found to be composed of cancer cell nests with scattered peripheral palisading in the dermis. Immunohistochemically, the tumor cells were positive for cytokeratin (CK) 7 and CD56 and were negative for CK20, synaptophysin, and chromogranin A. Membrane-bound dense-core granules were detected on ultrastructural study. A HBCC case with neuroendocrine differentiation has not been previously reported. The correlation between the presence of neuroendocrine differentiation in HBCC and patient prognosis should be further studied.

An autopsy case report of Trousseau's syndrome caused by intrahepatic cholangiocarcinoma is presented, and seven previously reported cases are reviewed. A 73-year-old woman experiencing light-headedness and dementia of unknown cause for 6 months developed severe hypotonia. A hypointense lesion compatible with acute cerebral infarction was detected by magnetic resonance imaging. Abdominal computed tomography revealed an ill-defined large liver mass in the right lobe. The mass was not further investigated because of the patient's poor condition. She died of multiple organ failure, and an autopsy was conducted. Postmortem examination revealed intrahepatic cholangiocarcinoma, fibrous vegetations on the mitral valves and multiple thromboemboli in the cerebrum, spleen and rectum. Trousseau's syndrome is defined as an idiopathic thromboembolism in patients with undiagnosed or concomitantly diagnosed malignancy. This syndrome is encountered frequently in patients with mucin-producing carcinomas, while the incidence in patients with intrahepatic cholangiocarcinoma is uncommon. We found that tissue factor and mucin tumor marker (CA19-9, CA15-3 and CA-125) expression in cancer cells may be involved in the pathogenesis of thromboembolism. A patient with unexplained thromboembolism may have occult visceral malignancy; thus, mucin tumor markers may indicate the origin of a mucin-producing carcinoma, and postmortem examination may play an important role in revealing the hidden malignancy.

The diffuse sclerosing variant of papillary thyroid carcinoma (DSV-PTC) is a relatively rare tumor. We herein report the case of young woman with DSV-PTC who developed cervical lymph node recurrence 7 years after the initial surgery. A 15-year-old female patient with no medical or family history of thyroid tumors developed a thyroid neoplasm in the right lobe. Right thyroidectomy and regional lymphadenectomy were performed, and the tumor was diagnosed as DSV-PTC. She was followed up as an outpatient. Seven years after the surgery, cervical lymph node recurrence developed. On microscopic examination, the thyroid tumor showed a papillary growth pattern with numerous psammoma bodies and distinct fibrosis. Immunohistochemically, the tumor cells were estrogen receptor and progesterone receptor positive with reduced membranous expression of E-cadherin and were intermingled with S-100-positive dendritic/Langerhans cells. DSV-PTC is characterized by a strong tendency for invasion and metastasis. Thus, accurate diagnosis is clinically important, and a morphological and immunohistochemical understanding of DSV-PTC is necessary.

We performed immunohistochemical studies of epithelial keratins in intraductal carcinoma in situ (IDCIS) in mammary Paget’s disease (MPD). K7, K8 and K18 were expressed in IDCIS in MPD. However, K19 was not expressed in IDCIS in MPD. Interestingly, K17 was expressed in some tumor cells in IDCIS. K17, a hyperproliferative keratin, may suggest ductal invasion and poor prognosis in MPD.

A 56-year-old Japanese woman who underwent a curative resection of ascending colon cancer at 43 years of age was found to have a tumor in her lower left abdominal cavity by computed tomography at 53 years of age. The tumor in the omentum was resected and identified as an adenocarcinoma compatible with metastasis from the primary ascending colon cancer. Although the patient received adjuvant chemotherapy with tegafur uracil and calcium folinate, liver metastasis was detected 9 months after the first recurrence. A segmentectomy and hepatectomy was performed, and histopathological findings indicated metastasis from the primary colon cancer. A third recurrence was detected in the right abdominal cavity 7 months after the second surgery. The patient received 5 cycles of combination chemotherapy consisting of folinic acid, fluorouracil and irinotecan before the third operation. The metastatic tumor resection together with intraperitoneal chemotherapy was performed, and histopathological findings indicated metastasis from the primary colon cancer. After the third surgery, the patient received adjuvant chemotherapy consisting of 5 cycles of folinic acid, fluorouracil and oxaliplatin. The patient is well with no evidence of recurrence 12 months after the third recurrence. This case suggests that colon cancer can be dormant for over 10 years and that long-term follow-up is required after curative resection. Aggressive local as well as systemic chemotherapy may be required for the management of colon cancer recurrence.

A 57-year-old Japanese woman with schizophrenia, who had received long-term treatment with neuroleptics, noticed a painless, pea-sized lump in her right breast. She was admitted to our hospital and a malignant tumor was diagnosed. The patient underwent a conservative radical mastectomy (Patey’s operation). The excised tumor measured 2.0 × 1.2 × 1.1 cm in diameter, and its cut surface was grayish-white. Histologically, tumor cells with clear to foamy cytoplasm were invariably Oil Red O-positive and periodic acid Schiff-negative with or without diastase digestion. The tumor was diagnosed as a lipid-rich carcinoma accompanied by an in situ component. Neuroleptics increase serum prolactin levels by interfering with dopaminergic inhibition of prolactin secretion. Immunohistochemical analysis revealed that, although prolactin was not detected, the tumor cells expressed prolactin receptor, indicating prolactin as the genesis of this neoplasm. In immunohistochemical intrinsic subtype analysis, the tumor was negative for estrogen receptor, progesterone receptor, human epidermal growth factor receptor 1 and 2, and basal cytokeratins (CK5, CK6, and CK14), indicating an unclassified (all-marker negative) subtype. Axillary lymph nodes were free of metastasis (stage I), and the patient has been well for 20 years without any evidence of recurrence.

Mesenteric liposarcoma is a rare neoplasm. Here, we report the case of a 73-year-old Japanese man with a well-differentiated (WD) liposarcoma of the mesentery. Due to rapid growth of the abdominal mass and abdominal insufficiency, a tumorectomy was performed. The excised tumor was 12.4 × 9.6 cm in size and weighed 548 g. Cut sections showed a lobulated yellow and/or grayish-colored appearance. The histological features were predominantly those of the sclerotic and lipoma-like variants of WD liposarcoma. The cytoplasm of most spindle cells was diffusely immunoreactive for CD34, while fat cells were positive for S-100 protein. Some spindle cell nuclei were positive for CDK4, and a few were positive for MDM2. The average Ki-67 proliferation index in tumor cells was 10%, and androgen receptor expression was detected in tumor cell nuclei. The present case and 11 cases identified from a literature search were reviewed. The WD mesenteric liposarcomas developed in patients in the fourth to seventh decades of life (mean age 57.9 years). The patients consisted of 7 men and 5 women. All tumors were larger than 10 cm in diameter at the time of surgery. Complete resection might be the only curative therapy for WD liposarcomas of the mesentery, but long-term follow-up is needed because of the possibility of a local recurrence of the tumor.

Multiple pilosebaceous cysts include the entities of steatocystoma multiplex and eruptive vellus hair cysts (EVHCs). Multiple pilosebaceous cysts are proposed to be one entity originating in the pilosebaceous duct, since steatocystoma multiplex and EVHCs are frequently present concomitantly and are caused by a cystic change in the same pilosebaceous duct. Here, we describe a patient with yellowish papules, 3–8 mm in diameter, on the neck and skin-colored or light-brown papules, 1–3 mm in diameter, on the neck, chest and upper abdomen. The smaller cysts were histopathologically diagnosed as EVHCs. The larger cysts had both features of EVHCs and steatocystoma multiplex. Therefore, a diagnosis of these lesions was made as multiple pilosebaceous cysts. Our case supports the proposition that multiple pilosebaceous cysts are a more appropriate diagnosis than the terms of EVHCs and steatocystoma multiplex.