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A case of a solitary, unilateral, large metastatic renal tumor found 35 years after the detection of primary thyroid carcinoma is presented. Renal metastasis from thyroid carcinoma detected during life is extremely rare, and there may be a long latency period before the appearance of a secondary tumor. The possibility of a secondary tumor should always be considered in the differential diagnosis of renal neoplasms, even when the tumor is a large, unilateral, solitary renal mass.

Aims and Background: Dermoscopy (dermatoscopy, skin surface microscopy, epiluminescence microscopy) has been increasingly employed in recent years for the preoperative detection of cutaneous melanoma, and dermatoscopic features of pigmented skin lesions have been previously defined using histopathology (HP) as the "key to the code". The aim of the present study was to evaluate the interobserver agreement on the HP diagnosis in a series of epiluminescence microscopy equivocal melanocytic skin lesions., Study Design: Ten melanocytic skin lesions were selected on the basis of diagnostic disagreement of at least 2 out of 9 epiluminescence microscopy observers. The histologic specimens from the 10 lesions were examined by 9 HP observers. The agreement of the HP diagnoses was calculated by means of Fleiss' k statistics., Results: The overall HP agreement was less than excellent (k = 0.5). When considering the prevailing epiluminescence microscopic and HP diagnoses, 2 cases were shown to be epiluminescence microscopy false-negative melanomas. Virtually no agreement was found among epiluminescence microscopy observers in 4 cases (40%) or among HP observers in 3 cases (30%). However, only one pigmented skin lesion remained unclassifiable on epiluminescence microscopy as well as HP., Conclusions: When at least 2 epiluminescence microscopy experts disagree in the evaluation of a given melanocytic skin lesion, even HP consultations may give equivocal results. The need to establish more reliable epiluminescence microscopic and HP criteria by performing an improved and meticulous clinicopathologic correlation, e.g. by using telecommunication via Internet, is emphasized.

Epithelioid hemangioendothelioma is an uncommon vascular tumor of the soft tissues. Several reports have described this tumor in visceral locations such as liver, lung, and brain. To the best of our knowledge this is the first report of an immunohistochemical and ultrastructural study of a primary epithelioid hemangioendothelioma occurring in the larynx. Difficulties concerning the differential diagnosis and clinical problems arising from surgical therapy in the laryngeal area are also discussed.

Granular cell tumors have been described in many sites throughout the body. To our knowledge, few cases have been described in the literature. We report here the sixth case, in which positivity for lysozyme was also observed for the first time. The problems of the histogenesis and differential diagnosis of this rare variant of basal cell carcinoma are also discussed.

Histiocytosis X rarely involves the thyroid gland and occurs as one of the unusual manifestations of systemic diseases. Diagnosis is based on the identification of the Langerhans' cells in an appropriate background. We report a case of histiocytosis X confined to the thyroid gland that represents the primary manifestation of the disease. A careful histological, immunohistochemical and ultrastructural study has been performed and problems of differential diagnosis are discussed.

We report a case of pilomatrix carcinoma in a 42 year old woman. The patient presented a rapidly growing 4-cm subcutaneous mass in the right preauricular area. She was free of recurrence 24 months after surgery. Immunoreactivity was studied for cytokeratins, epithelial membrane antigen, S-100 protein, blood group antigens, Leu-M1, beta-2-microglobulin, vimentin, neuron-specific-enolase and cellular binding for peanut agglutinin. Squamous cells were reactive for cytokeratin AE1/3, epithelial membrane antigen, blood group antigens B and H, and peanut agglutinin. Basaloid cells were focally reactive for cytokeratin AE1/3 and epithelial membrane antigen. Flow cytometry revealed a euploid DNA content and a high proliferative rate of the pilomatrix carcinoma and in benign pilomatrixoma studied for comparison. The pathological diagnosis must be based on histomorphological criteria.

Two cases of smooth muscle tumor of the breast with high tendency to local relapses are reported. The common cytohistologic feature of these infrequent neoplasms is interfacing bundles with spindle-shaped cells showing eosinophilic cytoplasm and blunt-ended nuclei. In estimating the prognosis of these lesions, the mitotic index must be evaluated together with evidence of necrosis and hypercellularity. The present cases suggest that, in the absence of the ancillary features, a mitotic rate of 1-3 x 10 HPF might define a "grey zone" in the spectrum of lesions between leiomyomas and leiomyosarcomas: the smooth muscle tumors of indeterminate prognosis (low risk lesions).

A moderately differentiated neuroendocrine carcinoma of the larynx is described. Although the patient had normal serum calcitonin level 36 months before, its level was elevated at the time the neck node was removed. This study supports the hypothesis that a diagnosis of calcitonin-producing neuro-endocrine tumor of the larynx with increased plasma calcitonin is possible and should be considered to avoid unnecessary thyroidectomy.

We report a case of intracystic papillary carcinoma of the male breast in a 70-year-old male Caucasian. Grossly, the tumor was a cystic lesion measuring 6 cm in diameter. It contained hemorrhagic fluid and a mural nodule with filiform projections. PAS stain with and without digestion revealed small clumps of diastase-resistant material in the cytoplasm of the neoplastic cells. Grimelius stain was positive. Immunoperoxidase stains were negative for neuron-specific enolase, S100 protein, cromogranin and synaptophysin and were positive for carcinoembryonic antigen and epithelial membrane antigen. On ultrastructural examination the neoplastic cells showed membrane-bound, dense-core secretory granules. We believe that this neoplasm, despite negative neuroendocrine markers, is a variant of mammary adenocarcinoma with endocrine differentiation, partly because of the positive Grimelius stain and partly because of the presence of electron-dense granules, which according to some authors represent lactational differentiation.

Malignant fibrous histiocytoma (MFH) of the upper respiratory tract is rare. We report a case of laryngeal MFH in a 78-year-old man. The patient died 8 months after the first surgical treatment. The clinicopathologic features are described, and the importance of electron microscopy and immunohistochemical techniques in the differential diagnosis with so-called "sarcomatoid carcinoma" is stressed. The tumor has an aggressive biological behavior and tends to recur and metastasize.

A retrospective study of 28 cases of thymoma classified according to Marino and Müller-Hermelink (cortical, medullary, mixed common, mixed with cortical predominance, mixed with medullary predominance thymoma) was undertaken to determine the existence of correlations between histology and clinical behavior. Cortical thymoma was observed in 11 cases (39.2%), mixed common thymoma in 9 (32.1%), mixed with cortical predominance in 5 (18%), and medullary thymoma in 3 (10.7%). In patients with cortical thymoma the tumor was always invasive (stages II and III according to Bergh), whereas medullary thymomas were noninvasive in 2 cases (stage I) and slightly invasive with a moderate infiltration of the capsule in the remaining case (stage II). Mixed common and mixed with cortical predominance thymomas displayed intermediate behavior. Twelve patients were affected by myasthenia gravis: 1 had medullary thymoma, 6 had mixed common thymoma, 3 had mixed thymoma with cortical predominance, and 2 had cortical thymoma. One patient with cortical thymoma had superior vena cava syndrome and 1 had erythroid hypoplasia; mixed common thymoma was associated with Cushing's syndrome in 1 patient. These data confirm previously reported observations (16) showing a higher degree of malignancy in patients with cortical thymoma.

A case of in situ and invasive ductal carcinoma with areas of squamoid differentiation arising in a phyllodes tumor is reported. This last aspect has never been described before and is discussed reviewing the previously reported cases in the literature.

A benign tumor of nerve sheath origin occurring in the dermis of a thumb is described. Histologically, these lesions contained nests and cords of large cells surrounded by thin bands of collagen fibers scattered in a myxoid background. The immunocytochemical reaction for S-100 protein was positive.