Rhabdoid carcinoma of anal canal: role of electron microscopy and immunohistochemistry in establishing lineage.

ABSTRACT Rhabdoid carcinoma is a high-grade carcinoma with rhabdoid features and it is different from rhabdoid tumors that are broadly defined as malignant neoplasms with rhabdoid cellular appearance found primarily in the pediatric population, but adult cases have been reported in many anatomic locations. To date, no cases of anal canal rhabdoid carcinoma have been reported in the adult or pediatric population. We are reporting the first case of anal canal rhabdoid carcinoma, found in a 75-year-old male. We utilized ultrastructural as well as immunohistochemical studies to arrive at our diagnosis. Ultrastructural studies demonstrated the intermediate filament congregating to impart a rhabdoid appearance to tumor cells, and cytokeratin intermediate filaments and short microvilli indicating nature of tumor as carcinoma. Immunohistochemical phenotype showed neoplastic cells were positive for vimentin, pan-cytokeratin AE1/3, p63 and D2-40, which supports the genesis of tumor from skin adnexa. Even in the modern era of surgical pathology that routinely utilizes immunohistochemistry and molecular studies, adequate use of electron microscopy to help pinpoint the diagnosis in challenging cases is important.

Unusual thyroid carcinoma with excessive extracellular hyaline globules: a case of "hyalinizing papillary carcinoma".

We present an unusual case of papillary thyroid carcinoma in a 47-year-old Japanese woman. The tumor, 0.8 cm in diameter, was located in the upper left lobe of the thyroid. Histologically, we observed a microfollicular-like and trabecular arrangement of the tumor cells with marked hyalinized stroma and hyaline globules. Immunohistochemically, tumor cells were positive for thyroglobulin and thyroid transcription factor 1. Hyaline stroma and globular bodies were immunopositive for laminin and type IV collagen. MIB-1 index was approximately 1% without membranous immunoreactivity. Under the electron microscope, hyaline stroma and globules showed electron-dense, complex meshwork structures composed of granular and fibrous elements similar to the structure of the lamina densa. Genetic analysis demonstrated a BRAF(V600E) mutation. Based on these findings, we diagnosed the present tumor as a rare morphological variation of papillary thyroid carcinoma with excessive hyaline globules consisting of basal membrane materials.

Postirradiation epithelioid angiosarcoma of the breast: a case report with immunohistochemical and electron microscopic study.

A case of postirradiation epithelioid angiosarcoma of the breast in a 72-year-old woman is reported. She had had right breast conserving surgery, axillary lymph node dissection, and 50 Gy external beam radiation therapy for infiltrating ductal carcinoma. A skin lesion on the irradiated breast appeared 5 years after completion of radiation. Angiosarcoma was diagnosed in a contralateral axillary mass 8 months later. Light microscopically, the tumor was characterized by a sheet-like growth of epithelioid cells with focal vasoformative areas. Tumor cells were reactive for factor VIII-related antigen, cytokeratin and CD34. Electron microscopically, the tumor cells were round with smooth cell borders. They were closely apposed, occasionally forming a small lumen containing single red blood cells or aggregates of platelets. Groups of tumor cells were enclosed by an external lamina. The tumor cells had abundant cytoplasm with sparse organelles. Rare suggestive Weibel-Palade bodies were present. The immunohistochemical and ultrastructural findings in this postirradiation tumor were in agreement with previously reported findings in non-irradiation-induced epithelioid angiosarcomas.

Meningioma presenting as an intraoral mass in a patient with neurofibromatosis type 1.

A 77-year-old woman with neurofibromatosis type 1 presented with ill-fitting dentures due to intraoral extension of a right temporal fossa mass. Computed tomographic scanning demonstrated that the masticator space mass bowed the zygomatic arch and remodeled the lateral orbit and maxillary sinus walls, findings that were consistent with the clinical diagnosis of a neurofibroma with possible malignant transformation. However, light microscopic, immunohistochemical, and ultrastructural examination of tissue from an incisional biopsy specimen were diagnostic of meningioma. This case illustrates that the clinicopathologic differential diagnosis of an enlarging mass in patient with neurofibromatosis should include sporadic, unrelated neoplasms as well as tumors known to be associated with the syndrome.

Angiomatoid (malignant) fibrous histiocytoma as a second tumour in a child with neuroblastoma.

Neuroblastoma occurring as a disseminated disease in children has a poor prognosis. Haematogenous metastases usually involve the marrow, bone, liver and skin. A second neoplasm may also develop. We describe a child with retroperitoneal neuroblastoma (stage 3) who developed a nodular mass in the inguinal area which was suspected to be a metastasis. Histopathology disclosed an angiomatoid (malignant) fibrous histiocytoma, and excision was curative. The occurrence of angiomatoid (malignant) fibrous histiocytoma as a second tumour in a patient with neuroblastoma has not previously been reported.

Malignancy after retinoblastoma: secondary cancer or recurrence?

The risk of second malignancy after retinoblastoma is reported to be as high as 20% at 10 years after initial diagnosis. This incidence may be an overestimate because of difficulties in distinguishing a second malignancy from recurrent tumor. We encountered a patient with bilateral retinoblastoma who developed a temporal mass 3.5 years after initial treatment for what had first been diagnosed as rhabdomyosarcoma; further study suggested that it was recurrent retinoblastoma manifesting as primitive neuroectodermal tumor (PNET) with multilineage differentiation. Chromosome 13 abnormalities were compatible with either rhabdomyosarcoma or recurrent retinoblastoma. To determine how often second malignancies in retinoblastoma patients may be confused with recurrent primary tumor, we reviewed our experience at Children's Hospital of Pittsburgh. Of 43 retinoblastoma patients seen between 1951 and 1992, presumed second malignancies were documented in four, including the current case. Of the three other second tumors, one had both neural and skeletal muscle differentiation; another was diagnosed as rhabdomyosarcoma unclassifiable as embryonal or alveolar; the last was an osteosarcoma. Only the osteosarcoma was clearly a second neoplasm; two and perhaps three of the other cases may be recurrent retinoblastoma. The distinction between second malignancy and recurrent retinoblastoma may be difficult but is worth determining, because treatment may differ, depending on the correct designation.

Carcinoma arising in ectopic hamartomatous thymoma. An ultrastructural study.

We present the ultrastructural features of a case of adenocarcinoma arising in ectopic hamartomatous thymoma in a 31 year old man, in the supraclavicular location. The tumor had a cribriform adenomatous component with a granular cell quality and mimicked a metastatic carcinoma. Ultrastructurally, the spindle cell component revealed clusters of tonofilaments and the tumor cells were attached by well developed desmosomes. The cytoplasm of adenocarcinoma cells contained peculiar cup-shaped bodies derived from the endoplasmic reticulum wrapped around the mitochondria.

Epithelioid hemangioendothelioma with multiple site involvement. Literature review and observations.

This report is a case of epithelioid hemangioendothelioma presenting as multiple lytic lesions of the ilium with radiographic findings of diffuse, bilateral lung involvement and biopsy-proven scalp involvement. Histologically, the tumor within bone and skin exhibited cords and nests of plump, epithelioid-appearing cells exhibiting rudimentary vascular differentiation within a myxohyaline stroma. Aggressive histologic features were not present. Immunohistochemical reactivity for Factor VIII-related antigen, Q-bend 10 (CD34), and cytokeratin were demonstrated. Ultrastructural studies revealed abundant intermediate cytoplasmic filaments, pinocytotic vacuoles, and Weibel-Palade bodies. The concurrent bone, skin, and lung involvement, low-grade histologic type, and female sex of the patient aroused speculation about the role of hormones in the development and possible treatment of the tumor, but estrogen and progesterone receptors were not detected. Despite intense combination chemotherapy, the patient died of widely metastatic disease. This report demonstrates the aggressive potential of histologically low-grade epithelioid hemangioendothelioma and the need for a thorough evaluation for metastases.

Two rare manifestations of melanomas: generalized cutaneous melanosis and rapid solar induction of showers of small pigmented lesions. A critical review of the literature and presentation of two additional cases.

Two unusual patients with metastatic melanoma are presented. One had generalized melanosis, and the other a rapid induction of multiple small pigmented lesions within a day of exposure to the sun. From a variety of clinical observations on these 2 patients and ones reported in the literature, and from recent advances in basic biomedical knowledge, we conclude that in both conditions the anomalous presence of growth factors that stimulate the proliferation and melanogenic differentiation of normal and malignant melanocytes played a major role in producing the clinical events.

Sinonasal primitive neuroectodermal tumor arising in a long-term survivor of heritable unilateral retinoblastoma.

BACKGROUND: Patients who survive retinoblastoma (RB) are at risk for having second nonocular tumors, usually osteosarcomas, which often are fatal. Such patients almost always have bilateral RB. METHODS: This article reports a woman who, at the age of 1 year had been cured of a unilateral RB by radiation therapy and enucleation. Eighteen years later, she had a sinonasal small cell tumor that rapidly recurred and proved fatal 2 months after surgical debulking. The tumor was studied by immunohistochemistry and electron microscopic (EM) examination. RESULTS: It showed diffuse neuron-specific enolase staining, focal weak staining for chromogranin, synaptophysin, and Leu-7 monoclonal antibodies in paraffin-embedded, B5-fixed tissue (Great Lakes Diagnostics, Troy, MI). EM study showed an undifferentiated primitive neuroectodermal tumor with many polyribosomes, simple cell junctions, few microtubules, and rare dense core granules. CONCLUSIONS: The combined immunohistochemical, ultrastructural, and clinical features of the tumor were interpreted as a sinonasal primitive neuroectodermal tumor with early neuronal differentiation. The tumor was pathologically indistinguishable from poorly differentiated olfactory neuroblastoma (ONB) and Ewing sarcoma.