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11/705. Tc-99m DTPA used as reference imaging to evaluate the distribution of other tumor-seeking tracers in tumors associated with neurofibromatosis.

    Two patients with multiple benign and malignant tumors associated with neurofibromatosis underwent radionuclide imaging with Tc-99m DTPA, Tl-201, and Ga-67. In these patients, Tc-99m DTPA accumulated intensively in both the benign and malignant tumors and localized and defined the extent of every tumor. In contrast, Ga-67 and Tl-201 uptake was seen only in focal areas of tumor where there was malignant transformation or at sites that showed progressive tumor growth. Tc-99m DTPA imaging accurately demonstrated areas of neoplastic involvement and identified the areas that would be seen with the other two tracers in individual tumors. Tc-99m DTPA may not always be used for the differential diagnosis of malignant and benign tumors of neurofibromatosis, but it can provide a reference pattern for imaging to evaluate accurately the distribution of Tl-201 and Ga-67 by mapping out the anatomic extent of these tumors.
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12/705. Malignant transformation of an optic disk melanocytoma.

    PURPOSE: To report a case of malignant transformation of an optic disk melanocytoma with a second melanocytoma in the ciliary body. methods: Clinical data including visual acuity, visual fields, color fundus photographs, fluorescein angiogram, and ultrasonogram and histopathologic studies of this case were reviewed. RESULTS: The right eye of a 65-year-old white woman was diagnosed with melanocytoma of the optic nerve. Four years later, the tumor became significantly larger. The best-corrected visual acuity declined from 20/40 to counting fingers and the size of the tumor increased fourfold in 2 years. The right globe was enucleated. Histopathologic studies demonstrated moderately pigmented spindle-B malignant melanoma cells adjacent to and within a population of large, polyhedral, heavily pigmented melanocytoma cells that extended to the lamina cribrosa and optic nerve. There was also a deeply pigmented melanocytoma in the ciliary body. CONCLUSION: This is a rare case of malignant melanoma transformed from an optic disk melanocytoma. Periodic follow-up of the patient with optic disk melanocytoma is necessary.
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13/705. Secondary myeloid/natural killer cell precursor acute leukemia following essential thrombocythemia.

    The de novo leukemic transformation of essential thrombocythemia is a rare event, and usually associated with previous treatments. We describe a patient who received treatments with nitrosourea for long-standing essential thrombocythemia and subsequently developed extramedullary tumors, tentatively diagnosed as lymphoblastic lymphoma. Combination chemotherapy was initially successful, but relapsed with marked bone marrow involvement. Surface marker analysis revealed that the tumor cells had CD5, CD7, CD33, CD34, and CD56 antigens but lacked other T-cell, and B-cell markers. Immunogenotypical studies revealed germline configurations for both T-cell receptors and immunoglobulin genes. These clinical and phenotypical features are consistent with a myeloid/natural killer cell precursor leukemia, a recently proposed distinct clinical entity. To our knowledge, this is the first report of secondary leukemia of myeloid/ natural killer cell precursor origin, and suggest that myeloid/natural killer cell precursor might be a potent target of therapy-related leukemia.
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14/705. Squamous cell carcinoma arising in a Warthin's tumor.

    Warthin's tumor is a well-defined salivary gland neoplasm consisting of epithelial and lymphoid components. However, malignant transformation is extremely rare. Such a patient who developed squamous cell carcinoma within a Warthin's tumor of the parotid gland is described and possible pathogenesis is discussed.
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15/705. Gastric adenocarcinoma associated with fundic gland polyps in a patient with attenuated familial adenomatous polyposis.

    Familial adenomatous polyposis (FAP) is a rare autosomal dominant precancerous condition of the colon caused by mutations in the adenomatous polyposis coli (APC) tumor suppressor gene. FAP is characterized by the appearance of innumerable adenomatous polyps throughout the large bowel. Fundic gland polyps are the most common gastric lesion in FAP. It is generally believed that fundic gland polyps have little or no potential for malignant transformation in the population at large, and only a few case reports describe the development of high grade dysplasia or gastric adenocarcinoma associated with diffuse fundic gland polyposis in patients with FAP. We report the second case of gastric adenocarcinoma intimately associated with fundic gland polyposis in a family with an attenuated form of FAP. The patient had undergone routine screening per current guidelines because of his known mutation in the APC gene. This suggests that malignant transformation of fundic gland polyps in patients with FAP occur more frequently than previously believed. Current screening recommendations may not be sufficient for patients with FAP or its attenuated forms.
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16/705. Pronounced cystic transformation of the rete testis. MRI appearance.

    BACKGROUND: Cystic transformation of the rete testis is a little-known partial or complete obstruction of the spermatozoa-containing secretion of the head of the epididymis. Depending on its severity, either ectasia or a cystic transformation occurs, which spreads to the network of convoluted seminiferous tubules in the mediastinum testis. Findings in contrast-enhanced MRI examinations are characteristic and may help to differentiate this benign entity from malignant neoplasia. The authors present two pronounced cases in different stages, documenting the broad spectrum of possible involvement.
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17/705. Demonstration of HPV 24 in long-standing Heck's disease with malignant transformation.

    We report on the rare case of a 64-year-old European woman with a viral acanthoma of the oral mucosa of the clinical Heck type with unprecedented molecular-biological proof of HPV 24 dna and so far undescribed malignant transformation with a long existence of the vegetation. After surgical therapy a circumscribed relapse of viral acanthoma developed, which responded favourably to a combined antiviral and antiproliferative therapy with acitretin perorally and interferon, first subcutaneously, later intralesionally for 3 months.
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18/705. Richter's transformation presenting as an obstructing endobronchial lesion.

    A 60-year-old man with chronic lymphocytic leukemia presented to our institution with a recurring lingular pneumonia. On fiberoptic bronchoscopy, the patient was found to have an endobronchial mass obstructing the lingula and left upper lobe. biopsy specimens of the mass demonstrated anaplastic large cell lymphoma consistent with Richter's transformation. Only one case of endobronchial Richter's transformation has been previously reported in the literature. This was described as peribronchial and endobronchial leukemic infiltrates within the bronchial mucosa. We report the first case of an obstructive endobronchial mass secondary to Richter's transformation. The endobronchial mass was treated with a Nd-YAG laser to maintain airway patency while the patient underwent chemotherapy, resulting in complete resolution of the mass within the airway.
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19/705. leiomyomatosis peritonealis disseminata: does malignant transformation occur? A literature review.

    leiomyomatosis peritonealis disseminata (LPD) is a rare smooth muscle tumor. In the literature more than 100 cases have been described. LPD is characterized by multiple small nodules on the peritoneal surface, mimicking a malignant process with metastases, but generally demonstrates benign histologic features. Exposure to estrogen seems to play an etiologic role. Many patients have uterine leiomyomas as well. The diagnosis of LPD is easily made on biopsy. Reduction of estrogen exposure is generally sufficient to cause regression of LPD. Surgical castration or gonadotrophin releasing hormone agonists seem good alternatives in the case of progression or recurrence of LPD. In six patients a malignant leiomyosarcoma has been described shortly after the diagnosis of LPD was made. Five of these patients did not have uterine leiomyomas or exposure to exogenous or increased endogenous estrogen. The relationship with pregnancy in the sixth patient may be coincidental. Whether malignant transformation of LPD occurs remains uncertain. Characteristics of these patients differ from those of LPD patients and may indicate a high malignant potential, necessitating a different approach.
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20/705. Low-grade malignant perineurioma of the paravertebral column, transforming into a high-grade malignancy.

    A demarcated 6 x 5 cm right paravertebral tumor at the level of T6 in a 39-year-old male was removed surgically. Histologically, the tumor consisted of monomorphous benign-looking, low-cellular spindle cells embedded in desmoplastic stroma. Ten years later, the tumor recurred locally with metastasis to systemic organs, including the occipital skin. Malignancy was histologically evident by the increased cellularity, cellular atypia and mitotic activity. The patient died of respiratory failure at the age of 49. Retrospectively reviewed, the primary lesion was low-grade fibrosarcoma-like spindle cell tumor, with secondary transformation into a highly malignant form. The differential diagnoses included sclerosing epithelioid fibrosarcoma, low-grade fibromyxoid sarcoma and malignant peripheral nerve sheath tumor. Immunohistochemically, the spindle cells in the primary and recurrent tumors consistently expressed epithelial membrane antigen, vimentin, type 4 collagen and laminin. The tumor cells in the present case showed a differentiation toward perineurial cells, which are normally positive for these immunohistochemical markers. Hence, the appropriate diagnostic term should be 'malignant perineurioma', a subtype of malignant peripheral nerve sheath tumor.
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