A Cerebellar Tumor-to-Tumor Metastasis in a Patient With Von Hippel-Lindau Disease.

Tumor-to-tumor metastasis in the central nerve system is uncommon in our routine practice. Most reports include metastatic breast cancer into meningioma. Here we report a metastatic clear cell renal cell carcinoma (ccRCC) into a cerebellar hemangioblastoma in a patient with von Hippel-Lindau (VHL) disease. Imaging cannot distinguish metastatic ccRCC from primary cerebellar hemangioblastoma. Immuno-molecular studies are proven to be diagnostic. We also reviewed previously documented tumor-to-tumor metastasis of ccRCC to cerebellar hemangioblastoma in VHL disease. Lastly, we discussed potential mechanisms involved in the metastasis of ccRCC to hemangioblastoma in the cerebellum in patients with VHL.

Visceral Leishmaniasis With Blastocystis Co-infection: A Case Report.

Visceral leishmaniasis (VL) is a form of leishmaniasis, which causes significant mortality if untreated. The coexistence of VL with Blastocystis infection has not been well-documented in the literature. In this paper, we present the case of a 72-year-old male who experienced four months of recurrent diarrhea and later developed weight loss, fever, night sweats, and pancytopenia. The stool ova and parasite (O&P) examination revealed Blastocystis spp. vacuolar bodies and he was treated with metronidazole which resolved the diarrhea but not other symptoms. Further evaluation, including an abdominal Computed Tomogram (CT) scan and ultrasonography (USG), revealed splenomegaly. A splenic biopsy confirmed VL with numerous Leishmania amastigotes. Treatment with Amphotericin B led to clinical improvement. This paper discusses the clinical and diagnostic features of VL and Blastocystis, highlighting their differential diagnosis, and available treatments.

Cytokeratin-20 negative nodal Merkel cell carcinoma with regressed primary: a potential pitfall in interpretation of nodal metastasis.

Merkel cell carcinoma (MCC) is a rare, highly aggressive cutaneous neuroendocrine carcinoma that affects sun-damaged skin. Histologically, the tumor consists of round cells with fine chromatin positive for cytokeratin 20 in ~90% of cases. Rare cases of MCC can regress spontaneously and present as nodal metastasis. Nodal MCC of unknown primary can cause a potential pitfall as they can be misinterpreted as other neuroendocrine carcinomas such as small cell carcinoma. We report a case of nodal MCC with an atypical immunohistochemistry pattern presented as bilateral axillary lymphadenopathy in a 90-year-old man with a remote history of a skin lesion that healed spontaneously leaving a scar.

A Rare Case of Metastatic Hepatocellular Carcinoma to the Hard Palate.

Extrahepatic metastasis of hepatocellular carcinoma (HCC) to the head and neck is unusual, especially the oral cavity/maxillofacial region. Metastatic HCC to the hard palate, however, is particularly rare. The most common site of HCC metastasis is the lung, followed by lymph nodes, bone, and adrenal gland. Importantly, oral cavity metastatic HCC may be misdiagnosed as a primary malignancy, such as a salivary gland carcinoma. In this article, we describe a young woman with metastatic HCC to the hard palate that was initially diagnosed as an acinic cell carcinoma.

Cutaneous and Subcutaneous Perineuriomas in 2 Pediatric Patients.

Perineuriomas are rare benign peripheral nerve sheath tumors that can present in a variety of locations with varying histologic patterns, most commonly in young to middle-aged adults; they are particularly rare in the pediatric population. Perineuriomas have a distinctive constellation of morphologic, immunohistochemical, and ultrastructural characteristics that allows for distinction from other benign peripheral nerve sheath tumors. We present 2 cases of perineuriomas that arose as cutaneous lesions in children.

Five-year review of intraoperative pathology consultation in a single institution.

Intraoperative pathology consultation plays an important role in the management of surgical patients and is also a measure for quality control in surgical pathology. A retrospective study was conducted to review intraoperative consultation during a 5-year period at a single institution. There were 19,145 intraoperative pathology consultation cases, including 19,026 concordant cases, 71 (<1%) frozen discordant cases, 11 (<1%) gross discordant cases, and 37 (<1%) deferred cases. Among frozen discordant cases, the most common cause for discordance was histologic sampling error (52.1%), followed by misinterpretation (42.3%). The most common major (clinically significant) frozen discordance was histologic sampling error for skin margins (32.4%), followed by histologic sampling error for lymph node metastasis (13.5%). Although our discordant rate (0.43%) was lower than that in previously reported studies (2%-8%), our major discordant rate was relatively high (50%). This review suggests that deeper sectioning of the blocks could improve the quality of our intraoperative consultations.

SMARCB1/INI1-deficient pancreatic undifferentiated rhabdoid carcinoma mimicking solid pseudopapillary neoplasm: A case report and review of the literature.

BACKGROUND: SMARCB1/INI1-deficient pancreatic undifferentiated rhabdoid carcinoma is a very aggressive tumor that is rarely reported in the literature. The tumor has a predominant rhabdoid cell component and different patterns of growth have been reported. CASE SUMMARY: A 59-year-old woman presented with diffuse abdominal pain, increasing in severity and accompanied by weight loss, nausea, and vomiting. Imaging showed a pancreatic head mass. Fine needle aspiration demonstrated atypical epithelioid cells with a pseudopapillary growth pattern suggestive of solid pseudopapillary neoplasm. The excised neoplasm showed monotonous epithelioid and focally spindle cells with pseudopapillary structures, rhabdoid features, and loss of SMARCB1 protein expression with wild-type KRAS, consistent with a SMARCB1/INI1-deficient undifferentiated rhabdoid carcinoma. The patient's condition deteriorated rapidly following surgery and she expired 3 mo post operation. CONCLUSION: In this article, we report the first case of SMARCB1/INI1-deficient undifferentiated pancreatic rhabdoid carcinoma mimicking solid pseudopapillary neoplasm.

Rhabdoid Myomelanocytic Tumor (PEComa) of the Ovary: A Clinically Benign Case Followed for 7 Years.

A 3.0 × 2.5 cm rhabdoid myomelanocytic tumor was incidentally found in the left ovary of a 43-year-old black woman. The tumor cells were cytologically bland with minimal proliferation rate, multifocally weakly or moderately expressed TFE3, strongly expressed smooth muscle markers and SMARCB1/INI1, and focally expressed HMB45. They contained numerous paranuclear whorls of intermediate filaments that were verified by ultrastructure. No other lines of differentiation were detected within the tumor. Neither translocation nor increased number of copies of the TFE3 gene at Xp11.22 was detected by fluorescence in situ hybridization. The patient remains well, free of tumor, 7 years after surgery. A rhabdoid variant of myomelanocytic tumor is a rarity, with only a single case described previously.

Thymic Tumor With Adenoid Cystic Carcinoma-Like Features: A Study of a Clinically Favorable Case Followed for 9 Years.

Thymic tumors with adenoid cystic carcinoma-like features are true rarities, with only 6 cases reported. Our knowledge of their clinical behavior is insufficient. We present a case of a noninvasive cribriform tumor that was followed, including a 4-year period after tumor resection and radiation therapy, for a total of 9 years. The tumor was purely epithelial. It was positive for keratins (AE-1/AE-3, CK19, 34ßE12,CK5/6), MOC-31, P63, P40, CD10, and MYB, and was negative for myoepithelial or neuroendocrine markers. Presence of cell processes, desmosome-like junctions with tonofilaments and multifocally reduplicated basal lamina was noted on ultrastructural examination. Two signals of the MYB gene per cell were detected by fluorescence in situ hybridization. No monosomy or translocations of the gene were found. Although additional clinical studies are necessary, it seems that indolent behavior of cribriform noninvasive subset of these tumors may be anticipated.

An unusual self-limited clonal Mott cell proliferation with lymphoplasmacytic lymphoma-like features in a child with the Wiskott-Aldrich syndrome and Von Recklinghausen's neurofibromatosis.

Patients with the Wiskott-Aldrich syndrome are at high risk for development of lymphomas, which are predominantly extranodal and of the immunoblastic type. We present a case of a self-limited lymphoproliferation with features of lymphoplasmacytic lymphoma arising in a patient with the Wiskott-Aldrich syndrome. The patient also had stigmata of von Recklinghausen's neurofibromatosis. The tumor was composed of CD138+, IgGkappa+, CD20-, PAX-5- Mott cells and CD5-, CD10-, CD19+, CD20+, CD43- small lymphoid B-cells that partially expressed CD23. The lymphadenopathy spontaneously resolved after a period of less than a year, and the patient had remained free of detectable lymphoproliferation for almost 4 years. He then developed Burkitt's lymphoma of the left parapharyngeal space. It is remarkable that both known lymphoproliferations with features of lymphoplasmatic lymphoma arising in patients with the Wiskott-Aldrich syndrome, this one and the previously described one, have spontaneously resolved. This observation is truly intriguing and requires further clinico-pathologic studies.

Perineurioma of the adrenal gland.

The authors report the first case of perineurioma of the adrenal gland. The tumor was composed of elongated wavy spindle cells focally arranged in a fascicular pattern. It was positive for epithelial membrane antigen (EMA) and claudin-1, and was negative for S-100 protein and glial fibrillary acidic protein (GFAP). Electron microscopy showed long, slender cytoplasmic processes coated by discontinuos basal lamina and presence of many pinocytotic vesicles.

Pleomorphic sarcoma as a mimicker of sarcomatous carcinoma.

The fourth case of a poorly differentiated sarcoma histologically mimicking a sarcomatous carcinoma is reported. The tumor was focally weakly positive for keratin, moderately focally positive for epithelial membrane antigen, muscle-specific actin, smooth muscle actin, and calponin, and strongly diffusely positive for vimentin. The neoplastic cells were closely apposed, often without intervening intercellular matrix; the cell membranes were straight and contained desmosome-like junctions. The cytoplasm contained a moderate number of mitochondria, rough endoplasmic reticulum, ribosomes, and many vesicles. The karyotype was complex and many chromosomal rearrangements were present. The diagnostic term carcinomatoid sarcoma is proposed for these interesting, insufficiently studies, tumors.