Critical analysis of histologic criteria for grading atypical (dysplastic) melanocytic nevi

Low concordance in grading atypical (dysplastic) melanocytic nevi (AMN) has been reported, and no systematic evaluation is available. We studied 123 AMN with architectural and cytologic atypia (40 associated with atypical-mole syndrome), classified according to standard criteria by 3 independent observers. Histologic variables included junctional and dermal symmetry, lateral extension, cohesion and migration of epidermal melanocytes, maturation, regression, nuclear features, nuclear grade, melanin, inflammatory infiltrate location, and fibroplasia. AMN (43 junctional and 80 compound) were graded mild (31), moderate (61), and severe (31). AMN-severe correlated with 3 or more nuclear abnormalities (especially pleomorphism, heterogeneous chromatin, and prominent nucleolus) and absence of regression, mixed junctional pattern, and suprabasilar melanocytes on top of lentiginous hyperplasia. AMN-severe diagnostic accuracy was 99.5% using these criteria, but only the absence of nuclear pleomorphism differentiated AMN-mild from AMN-moderate. No architectural features distinguishing AMN-mild from AMN-moderate were selected as significant by the discriminant analysis. AMN from atypical-mole syndrome revealed subtle architectural differences, but none were statistically significant in the discriminant analysis. Histologic criteria can reliably distinguish AMN-severe but fail to differentiate AMN-mild from AMN-moderate. AMN from atypical-mole syndrome cannot be diagnosed using pathologic criteria alone.     

Pituitary siderosis. A histologic, immunocytologic, and ultrastructural study.

Pituitaries of 6 patients with various iron overload states have been studied by morphologic techniques, including immunostaining and electron microscopy. The immunoperoxidase technique combined with the prussian blue reaction revealed iron deposition in all five adenohypophysial cell types, indicating the iron uptake per se does not entirely block hormone storage. Iron distribution was uneven; more iron was demonstrated in PAS-positive cells than in orangeophils, and a preferential localization was disclosed in the gonadotrophs. In 2 cases of hemochromatosis, reduction of pituitary gonadotrophs was implicated in the genesis of hypogonadism. By electron microscopy, iron particles were noted in the cytoplasm of various adenohypophysiocytes, partly incorporated into lysosomes. Some adenohypophysiocytes with iron accumulation showed degranulation by light and electron microscopy and decreased hormone storage by the immunoperoxidase technique. Although these changes may be causally related to iron deposition, more work is required to prove that iron has a direct toxic effect on adenohypophysial cells.     

Spitz nevi and atypical Spitz nevi/tumors: a histologic and immunohistochemical analysis.

A subset of Spitz nevi poses substantial diagnostic difficulty, even among experts, due to its resemblance to malignant melanoma. These lesions are termed atypical Spitz nevi/tumors and there is currently a lack of objective criteria for predicting their biologic behavior. We compared the expression of Ki-67, p21, and fatty acid synthase by immunohistochemistry in 10 atypical Spitz nevi, 28 typical Spitz nevi, 19 compound melanocytic nevi and 18 invasive malignant melanomas. There was a progressive increase in fatty acid synthase cytoplasmic expression with statistically significant differences observed between Spitz nevi and atypical Spitz nevi (P=0.003) and between atypical Spitz nevi and malignant melanoma (P<0.050). Ki-67 nuclear staining was lower in both typical and atypical forms of Spitz lesions than in malignant melanoma (P<0.001). The degree of P21 nuclear expression in atypical Spitz nevi was not significantly different than in Spitz nevi, but was significantly greater than expression in conventional nevi and approached significance after multiple comparisons corrections for malignant melanoma. Thus, a high level of P21 expression makes a tumor more likely to be a typical or atypical Spitz nevus than a malignant melanoma, especially when coupled with a low Ki-67 index and weak expression of fatty acid synthase. These immunohistochemical observations support the concept that atypical Spitz nevi are distinct lesions of borderline biologic behavior residing between Spitz nevi and malignant melanoma. The study also compared a large array of histologic features of 16 cases of typical Spitz nevi in children with 12 typical Spitz nevi in adults. The adult lesions were significantly more likely to be intradermal and to display dermal fibroplasia, but were histologically similar to their pediatric counterparts in all other respects.     

Clinical, ultrastructural and biochemical studies in two sibs with Ehlers-Danlos syndrome type VI-B-like features

Two Turkish sibs with clinical features of Ehlers-Danlos syndrome type VI-B are presented. The hydroxylysine contents of dermis and gel electrophoresis of type I and type III collagen produced by fibroblasts were normal. Ultrastructural studies of skin collagen and elastic fibers showed discrete abnormalities. Other syndromes with similar clinical, biochemical and ultrastructural features are discussed.     

Clinical evolution, histologic type and general lymphographic picture in Hodgkin's disease.

In 88 patients with Hodgkin's disease the clinical value of the general lymphographic picture (lymphodynamic aspects plus nodal patterns) is analysed. The survival times are also reported according to the different pre- and postlymphographic evolution. Histologic types and prelymphographic therapy are correlated with the general lymphographic picture. The predominance of foamy and/or spotty lymphographic patterns of lymph nodes as well as the lymphatic blockages have a severe prognosis (mean intervals between lymphography and exitus 8.3 and respectively 6.2 months). In such cases lymphocytic depletion represents the most frequent histologic type.     

Acute monocytic leukemia. Cytologic, histologic, cytochemical, ultrastructural, and cytogenetic observations.

A case of acute monocytic leukemia (AMoL) studied by cytologic, histologic, cytochemical, ultrastructural, and cytogenetic technics is reported. The immature monocytes were characterized by strong fluoride-sensitive nonspecific esterase activity. Nuclear irregularity, prominent nucleoli, erythrophagocytosis, and pinocytosis were observed on transmission electron microscopy, whereas broad-based ruffles, similar to those found on normal monocytes, were identified with scanning electron microscopy. Cytogenetic analysis showed an 8/9 translocation and four or five identical 8p- marker chromosomes in most bone marrow cells.     

Congenital myofibroma. A true hemangiopericytoma. A neonatal case with immunohistochemical and ultrastructural studies

We report the case of a male newborn infant with a pedunculated dermic tumor, located in the right malar region; who underwent a complete surgical resection of the tumor and had a satisfactory postoperative evolution. The histopathologic findings disclosed a subcutaneous tumor with a nodular aspect and a subendothelial intravascular growth, constituted by a dual population of small cells and spindle-shaped cells, distributed in a biphasic pattern. All tumor cells showed a strong pericellular reaction for PAS. The immunohistochemical studies revealed: diffuse cytoplasmic positivity for CD34 and Vimentin in all tumor cells, and only spindle-shaped tumor cells and less differentiated isolated neoplastic cells, presented cytoplasmic positivity for the smooth muscle alpha-actin. The electronic microscopy demonstrated a layer of basal membrane and in the citoplasm, numerous intermediate filaments with focal condensations. Based on all these findings, we conclude that this is a myofibroma, a "true hemangiopericytoma" with myofibroblastic differentiation. For this reason, we propose the term myofibropericytoma, in order to highlight its pericytic origin and its myofibroblastic differentiation. We emphasize the need to recognize this entity, in view of its low frequency and the possibility of a diagnostic mistake with other soft tissues tumors that display haemangiopericytoma-like features.     

Coexistence of two lymphomas with distinctive histologic, ultrastructural, and immunologic features.

The unusual coexistence of two distinct lymphomas in 44-year-old woman is described. Nodular, poorly differentiated lymphocytic lymphoma and diffuse histiocytic lymphoma were present in separate sites and were readily distinguished both histologically and ultrastructurally. In addition, the lymphocytic lymphoma was shown to be derived from complement receptor B lymphocytes of follicular center cell type, whereas the histiocytic lymphoma cells were devoid of complement receptors, receptors for IgG (Fc receptors), and surface immunoglobulin. Despite intensive chemotherapy and radiation therapy, the patient died within eight months of the initial diagnosis. Although histiocytic lymphoma was widely disseminated at autopsy, lymphocytic lymphoma was not found. Presumably the histiocytic lymphoma was refractory to therapy, in contrast to the lymphocytic lymphoma, which was selectively eradicated.     

Pituitary adenomas in Cushing's disease. A histologic, ultrastructural, and immunocytochemical study.

Twenty-two pituitary adenomas in Cushing's disease were removed by transsphenoidal surgery. In six patients the pituitary tumor had become manifest following adrenalectomy (Nelson's syndrome). Sixteen tumors were microadenomas measuring from 2 to 9 mm, while two were diffuse invasive adenomas verified at postmortem examination. Light microscopy showed that the tumors were made of basophillic cells containing PAS-positive granules that stained blue with Herlant tetrachrome and lead hematoxylin. Immunocytochemical studies showed that the granules stained positively with antiserum to adrenocorticotrophic hormone (ACTH) or to beta-lipotropic hormone (beta-LPH) and the peroxidase-antiperoxidase complex. Electron microscopic study of the tumor cells showed ACTH and beta-LPH containing granules varying in size, shape, and amount. Perinuclear bundles of 70 A microfilaments constituted a specific ultrastructural finding.     

Benign lymphoepithelial cysts of the parotid gland. A histologic, cytologic, and ultrastructural study

Five cases of benign lymphoepithelial cysts (BLCs) of the parotid gland are reported, and the histologic, aspiration cytologic, and ultrastructural findings are described in detail. These uncommon parotid lesions contain epithelium-lined cystic spaces encased by abundant lymphoid tissue with germinal centers. The epithelium was "mucoepidermoid" in three of our cases and squamous in two. Familiarity with the morphologic features of BLCs should make it possible to distinguish them from similar-appearing cystic lesions, especially low-grade cystic mucoepidermoid carcinoma and cystic types of benign lymphoepithelial lesion (so-called Mikulicz's disease). These distinctions, however, are difficult on aspiration cytology specimens.     

Congenital hepatoblastoma of mixed type. Light and electron microscopy studies

Malignant liver tumors of infancy are uncommon. In this report the histological and ultrastructural features of a congenital mixed hepatoblastoma in a female infant are described. The tumor was obtained by radical surgery at the eighth day of life. Histologically the mass was characterized by a mixture of variously differentiated hepatic tissue and mesenchymal tissue. The epithelial component is represented by liver cells of the embryonic and fetal type. Electron microscopical investigation revealed a changing organelle composition of the epithelial tumor cells showing a decreased number of cytoplasmic organelles in the cells of the embryonic type. At cellular junctions, however, these cells are connected by desmosome-like structures without lumina as well as empty canaliculi-developing structures of cholangiolar microvilli. At light microscopical level the former corresponded to pseudorosettes , the latter to so-called rosettes. Furthermore, in places sinus-like structures are encountered but in the absence of true sinusoidal channels with Disse's spaces. Some areas consisted of undifferentiated cells lacking cytoplasmic organelles and resembled a multipotential blastema. The ultrastructural findings suggest that hepatoblastoma may arise from an undifferentiated progenitor cell capable of various forms of differentiation.     

Malignant mesothelioma: cytologic diagnosis with histologic, immunohistochemical, and ultrastructural correlation.

The differential diagnoses of malignant mesothelioma in serous effusions include adenocarcinoma and reactive mesothelial cells. While several cytologic features are of predictive value in separating these entities, immunostaining and ultrastructural examination are important adjuncts that increase the diagnostic yield. Many of the cytomorphologic features can be correlated with immunohistochemical and ultrastructural findings. Most important among these is the ultrastructural demonstration of long, often branching microvillous processes in malignant mesothelial cells. Corresponding microvilli can be visualized by immunostaining for epithelial membrane antigen in both cell block preparations from effusions and biopsy specimens, allowing the identification of malignant mesothelioma. In addition, the circumferential distribution of these immunostained microvilli in cells dispersed in stromal connective tissue identifies them as malignant mesothelial cells, corresponding to the ultrastructural appearance of aberrant microvilli, which project through deficiencies in the basal lamina. These microvilli show interdigitation with stromal collagen fibers, a phenomena not observed in adenocarcinoma.     

Human papillomaviruses of different types in precancerous lesions of the uterine cervix: histologic, immunocytochemical and ultrastructural studies

In a prospective study of 34 women with abnormal Papanicolaou smears, biopsy and cervicovaginal lavage specimens were analyzed for the presence of human papillomaviruses (HPVs) by Southern blot analysis and probes for HPVs 6, 11, 16, and 18. In 22 of the 23 patients with cervical lesions (96%), HPV DNA was identified in one or more specimens. All patients in whom HPV DNA was found had either koilocytotic or dysplastic lesions on biopsy or Papanicolaou smear. Immunocytochemical demonstration of HPV in biopsy samples was associated with the presence of large amounts of HPV DNA and with the ultrastructural identification of viral particles. The presence of HPV DNA in cervical biopsy specimens was limited to discrete geographic areas of the cervix with histologic abnormalities. Although HPV 16 and other related HPV types were found in all cases of severe cervical intraepithelial neoplasia, the type of HPV present in a given specimen could not be predicted on the basis of morphologic, immunocytochemical, or electron microscopic findings. It is concluded that virtually all dysplastic lesions of the cervix contain HPV DNA, that HPV is thus likely to be a major etiologic agent in the pathogenesis of cervical dysplasia, and that histopathologic features are not predictive of HPV type.     

Fine-needle aspiration biopsy diagnosis of rhabdomyosarcoma: cytologic, histologic, and ultrastructural correlations.

A series of 15 cases of rhabdomyosarcoma diagnosed by fine-needle aspiration biopsy (FNAB) and confirmed by histopathology is reviewed. Cytologically, the tumors were composed of a variable mixture of cells, which according to the degree of differentiation were categorized as early, intermediate, or late rhabdomyoblasts. Histologically, the tumors were divided into embryonal 9, monomorphic round cell 4, and alveolar rhabdomyosarcoma 2. Comparison of histological and cytological features revealed that embryonal types were composed mainly of early rhabdomyoblasts. Recognition of these patterns may be helpful in FNAB diagnosis of rhabdomyosarcoma.     

In vivo assessment of melanocytic nests in nevi and melanomas by reflectance confocal microscopy.

In vivo reflectance confocal microscopy is a novel technique for the noninvasive study and diagnosis of the skin. The aim of this study was to describe and characterize the cytological and architectural aspects of cell clusters in melanocytic lesions observed by confocal microscopy, and to correlate them with routine histopathology. A total of 55 melanocytic lesions comprising 20 melanomas, 25 acquired nevi and 10 Spitz nevi were studied by means of reflectance confocal microscopy, dermoscopy and routine histopathology. Three different types of cell clusters at confocal microscopy observation (dense, sparse cell and cerebriform clusters) were identified and correlated with histopathology. Dense clusters appeared characteristic for benign lesions, although present in 13 out of 20 melanomas. Sparse cell clusters were more frequently observable in melanomas, but also sporadically present in one Spitz nevus. Moreover, cerebriform clusters were exclusively observed in five out of 20 melanomas. Confocal microscopy allowed the in vivo characterization of aspects of melanocytic nests and their exact correlation with histopathology.     

Macroscopic, histologic, histochemical, immunohistochemical, and ultrastructural features of mesothelioma

Mesotheliomas are uncommon neoplasms that arise from the cells forming the serosal membranes of the body cavities. Approximately 90-95% of mesotheliomas arise in the pleural cavity and 5-10% in the peritoneal cavity. Rare mesotheliomas arise in the pericardium and in the tunica vaginalis. Unlike many neoplasms, mesotheliomas grow in a diffuse distribution and tend to encase the organs in the various body cavities. A combination of histochemical, immunohistochemical, and ultrastructural features are often necessary to accurately diagnose mesotheliomas. These techniques are highlighted in this review article on mesothelioma.