p53 protein expression and gene mutation in phyllodes tumors of the breast.

The malignant potential of mammary phyllodes tumors is difficult to assess on initial pathologic examination. Studies on the p53 tumor suppressor gene have shown that it has an important role in the development of a variety of malignancies, yet the specific contribution to the pathogenesis and development of the malignant potential of phyllodes tumor is largely unknown. We studied p53 protein expression in 25 cases of phyllodes tumors histologically classified as either malignant (12 cases) or benign (13 cases). Using microdissection approach, we also analyzed the p53 gene sequence in a case that demonstrated progression from benign to malignant phenotype. Nuclear p53 staining was detected in various proportions (1-90%) of neoplastic stromal cells of malignant tumors. No staining was found in benign tumors. Progression from benign to malignant phenotype was associated with a significant increase in the accumulation of p53 (more than 20 times). This was caused by an underlying missense mutation in exon 7, resulting in a change from Arg248 to Trp248 in the malignant component of the tumor. Stromal p53 over-expression was observed only in neoplasms histologically classified as malignant and was associated with an increased proliferation index (MIB-1 staining). These two markers may be used as useful adjuncts in the diagnosis of malignancy in difficult cases or when only a limited sample size is available. Somatic mutation in exon 7 of p53 gene in malignant phyllodes tumor points toward the importance of p53 in the malignant transformation of phyllodes tumors.

Different immunohistochemical patterns of Fhit protein expression in renal neoplasms.

BACKGROUND: The FHIT gene on human chromosome 3p14.2 is deleted in a variety of malignant tumors, including clear cell renal carcinomas (RCCs) resulting in a loss of expression of Fhit protein. The Fhit expression in specific subtypes of renal carcinomas has not been characterized. We have investigated the association of Fhit expression with particular subtypes of renal tumors to determine the role and specificity of this putative tumor suppressor gene in renal neoplasia. MATERIAL AND METHODS: The immunohistochemical expression of Fhit was tested in normal kidneys and in 109 renal neoplasms consisting of 51 clear cell RCCs, 26 papillary RCCs, two chromophobe carcinomas, six oncocytomas, four pelvic transitional cell carcinomas and 20 Wilms' tumors from formalin fixed and routinely processed tissue. RESULTS: Normal renal tubules expressed Fhit strongly and consistently. The majority (78%) of clear cell RCCs showed reduced or absent expression of Fhit, whereas the majority (74%) of papillary carcinomas, all chromophobe renal cell carcinomas, and oncocytomas were strongly positive. Sixty-eight percent of low-grade (G1 plus G2) but only 9% of high-grade (G3 plus G4) clear cell carcinomas were Fhit negative. Wilms' tumors demonstrated focal staining in the epithelial component in 8 of 20 cases (40%). CONCLUSIONS: The loss of Fhit expression in a high percentage of clear cell RCCs with conservation of Fhit in other types of tumors supports the proposed role of FHIT alterations in the genesis of clear cell carcinomas in contrast to other types of renal epithelial tumors. FHIT expression may play a role in epithelial differentiation of nephroblastomas (Wilms' tumors).

Diagnosis of primary fibrosarcoma of the lung by fine-needle aspiration and core biopsy.

Primary pulmonary sarcomas are uncommon neoplasms. Primary fibrosarcoma of the lung is extremely rare, and only 53 cases have been documented in the literature to date. To our knowledge, the diagnosis of primary lung fibrosarcoma by fine-needle aspiration cytology has never been reported. We report a case of pulmonary fibrosarcoma diagnosed by fine-needle aspiration cytology and core biopsy. The neoplasm consisted of interweaving fascicles of minimally atypical spindle cells with slender nuclei and scant cytoplasm. Positive immunohistochemistry for vimentin along with nonreactivity of tumor cells for keratin, S100 protein, desmin, alpha-smooth muscle actin, and CD34 supported the the diagnosis. The diagnosis was later confirmed by histologic and ultrastructural findings following lobectomy. A meticulous clinical search for a possible primary neoplasm elsewhere was unsuccessful, and lung was established as the primary site. Fine-needle aspiration cytology and core biopsy are reliable methods for establishing a diagnosis of fibrosarcoma.

Cutaneous verruciform xanthoma: a report of five cases investigating the etiology and nature of xanthomatous cells.

Verruciform xanthoma is a rare clinicopathologic entity of uncertain etiology that occurs primarily in the oral mucosa. Aggregates of foam cells in the submucosal stroma or papillary dermis in association with verrucous epithelial hyperplasia are the hallmark of this lesion. Extraoral (cutaneous) occurrence of verruciform xanthoma is much rarer and has been reported mostly in the genital skin. Five cases of extraoral cutaneous verruciform xanthoma (three from the scrotum, one from the penis, and one from the nose) and one histologic "simulant" (from skin of the nose) were studied. The lesions were solitary, raised, or polypoid with cup-shaped craters filled with parakeratotic cells that blended into keratinocytes of an acanthotic and papillomatous epidermis. There was a neutrophilic infiltrate of varying intensity between plump parakeratotic cells and keratinocytes, near the surface of the epidermis. Aggregates of foam cells were present in the papillary dermis, which was highly vascular. A plasma cell predominant infiltrate was seen at the base in a bandlike fashion. Despite the architectural resemblance of verruciform xanthoma to verrucous mucocutaneous lesions related to human papillomavirus infection, it was not detected by either immunohistochemistry, in situ hybridization, polymerase chain reaction, or Southern blot analysis in any case. The foam cells were weakly positive for cytokeratin and for Factor XIIIa but negative for S-100 protein. The KP1 and Mac 387 immunostain showed focal weak staining in foam cells. We postulate that a cascade of events pursue after initial keratinocytic damage attracting neutrophils, with subsequent phagocytosis of necrotic keratinocytic debris by dermal dendrocytes, eventually leading to the ultimate manifestation of the lesion as verruciform xanthoma. The etiologic agent remains elusive, but based on our findings, we conclude that verruciform xanthoma is most likely not a human papillomavirus-associated squamoproliferative lesion and that the foam cells, a histologic hallmark of the lesion, are most likely derived from dermal dendritic cells.