Cellular blue nevus is an benign variant of blue nevus group, characterized by cellular islands composed of closely aggregated spindle cells with little or no melanin. The other variants include atypical and malignant blue nevus which often had the difficulties in the differential diagnosis from the malignant melanoma. A 4-year-old boy presented with hemispheric scalp nodule, which has been slowly grown since birth, measuring 3.5x3x1.5 cm. The surface showed geographic black pigmentation without hairs, hemorrhage, and ulceration. The excised mass disclosed homogeneoulsy dark black, glistening, and muddy cut surface. Histological examination revealed exuberant melanocytic proliferation with both spindle and dendritic components. Heavily pigment ed spindle cells, melanophages, focal necrosis, and vacuolated epithelioid cells were unusually noted in our case and diagnosed as cellular blue nevus. Electron microscopy disclosed largely mature melanosomes in tumor cells and melanophages. During about 16 months since operation, he has been relatively well with no evidence of disease.
Diagnosis, Differential

The authors report four cases of ependymal cysts. Among the benign cystic lesions of neuroepithelial origin, ependymal cysts have been reportedly located in the cerebral parenchyme. This usually become symptomatic after 40 years of age, although it is generally thought to be congenital in origin. Symptomatic cases have been treated effectively with resection of the cyst or shunting procedures. Stereotactic removal of the cyst was also a good alternative as management in the authors' cases. Differential diagnosis is mandatory with other benign intraparenchymal cystic diseases.
Diagnosis, Differential

The fine needle aspiration (FNA) cytologic findings in 16 cases of histologically confirmed thymoma are reported. The aspirates were obtained under fluoroscopic guidance. The cytologic diagnoses were inadequate sample in one case, thymoma in 12 (75%), small cell carcinoma or thymoma in 1, benign mesenchymal tumor in 1, and germ cell tumor in one. The cytologic features were detailed according to the constituent epithelial cell type, and to the ratio of epithelial cells and lymphocytes. Fifteen cases were classified into 4 small epithelial cell type, 6 intermediate epithelial cell type, 1 large epithelial cell type, 1 large pleomorphic epithelial cell type, and 3 spindle-shaped epithelial cell type. Cytologic differential diagnosis was discussed, and the important criteria for the cytologic diagnosis of thymoma were reviewed. This review leads us to think that nonoperative cytologic approaches in the diagnosis of the thymoma are possible, and that correct cytologic diagnosis of thymoma with FNAs can easily be made, if adequate samples are obtained. However, the invasiveness and histologic type could not be predicted by cytological features only. Knowing various cytologic and histologic features of thymoma will be helpful for the diagnosis of thymoma and the differential diagnosis of mediastinal tumors.
Diagnosis, Differential

BACKGROUND: Pleural fluid adenosine deaminase (ADA) activity can be helpful in a differential diagnosis of an exudative pleural effusion because it is increased in a tuberculous pleural effusion. The ADA activity is determined mainly by the lymphocyte function. Age-associated immune decline is characterized by a decrease in T-lymphocyte function. For that reason, the pleural fluid ADA level would be lower in older patients with exudative pleural effusion. This study focused on the influence of age on the pleural fluid ADA activity in patients with exudative pleural effusion. METHODS: A total of 81 patients with exudative pleural effusion were enrolled in this study. In all patients, the pleural fluid ADA activity was measured using an automated kinetic method. RESULTS: The mean age of the patients was 52.7+/-21.2 years. In all patients with exudative pleural effusion, the pleural fluid ADA activity revealed a significant difference between young patients (under 65 years of age) and old patients (at or over 65 years of age) : 82.8 +/- 48.0 IU/L in young patients Vs. 57.7+/-37.2 IU/L in old patients (p<0.05), and showed a negative correlation with age (r=-0.325, p<0.05). In the 60 patients with a tuberculous pleural effusion, the pleural fluid ADA activity revealed a significant difference between the young and older patients : 103.5+/-36.9 IU/L in young patients Vs. 72.2+/-31.6 IU/L in old patients (p<0.05), and showed a negative correlation with age (r=-0.384, p<0.05). In the 21 patients with non-tuberculous exudative pleural effusion, the pleural fluid ADA activity of the young patients and old patients was similar : 23.7+/-15.3 IU/L in young patients Vs. 16.1+/-10.2 IU/L in old patients (p>0.05), and did not show any correlation with age (r=-0.263, p>0.05). The diagnostic cutoff value of pleural fluid ADA activity for tuberculous pleural effusion was lower in the older patients (25.9 IU/L) than in the younger patients (49.1 IU/L) or all patients (38.4 IU/L) with exudative pleural effusion. CONCLUSION: Tuberculous pleural effusion is an important possibility to consider in older patients with a clinical suspicion of a tuberculous pleural effusion, although no marked increase in the pleural fluid ADA activity is usually detected. For a diagnosis of a tuberculous pleural effusion in old patients, the cutoff for the pleural fluid ADA activity should be set lower.
Diagnosis, Differential

The inflammatory pseudotumor of the lung is a non-neoplastic pulmonary mass lesion, composed of a variey of inflammatory cells including plasma cells, histiocytes(often xanthomatous), mast cells, lymphocytes, and spindle shaped mesenchymal cells. Although the pathogenetic etiology of this lesion is not estabilished, it has been claimed that it is associated with local inflammatory reaction. From 1984 to 1986, we experienced three cases of pathologically confirmed inflammatory pseudotumor of the lung. All three cases revealed similar gross and microscopic features, with only minor differences in components on microscopic level. All specimens were products of lobectomy. They showed a relatively well defined, yellowish white and solid mass, measuring about 5.0 cm in diameter. Histologically, the lesions, which were well demarcated from the uninvolved region, were characterized by dense infiltration of plasma cells and xanthomatous histiocytes admixed with lymphocytes, spindle shaped mesenchymal cells and polymorphonuclear leukocytes. At periphery, bronchi and bronchioles were entrapped by these cells. In focal areas, spindle shaped mesenchymal cells were aggregated, resulting in formation of thick bundles in which plasma cells were infiltrated. In case 1 and 2, myxoid change of stromal tissue was noted. Also noted were foci of osteoid metaplasia of the stromal layer in case 1. The authors report three cases of inflammatory pseudotumor of the lung, with comparative observation of each case, associated with literature review, with emphasis on the pathogenesis of this rather infrequent lesion. And some reviews were made on differential diagnosis between inflammatory pseudotumor and non-neoplastic or neoplastic lung mass including so called sclerosing hemangioma.
Diagnosis, Differential

The inflammatory pseudotumor of the lung is a non-neoplastic pulmonary mass lesion, composed of a variey of inflammatory cells including plasma cells, histiocytes(often xanthomatous), mast cells, lymphocytes, and spindle shaped mesenchymal cells. Although the pathogenetic etiology of this lesion is not estabilished, it has been claimed that it is associated with local inflammatory reaction. From 1984 to 1986, we experienced three cases of pathologically confirmed inflammatory pseudotumor of the lung. All three cases revealed similar gross and microscopic features, with only minor differences in components on microscopic level. All specimens were products of lobectomy. They showed a relatively well defined, yellowish white and solid mass, measuring about 5.0 cm in diameter. Histologically, the lesions, which were well demarcated from the uninvolved region, were characterized by dense infiltration of plasma cells and xanthomatous histiocytes admixed with lymphocytes, spindle shaped mesenchymal cells and polymorphonuclear leukocytes. At periphery, bronchi and bronchioles were entrapped by these cells. In focal areas, spindle shaped mesenchymal cells were aggregated, resulting in formation of thick bundles in which plasma cells were infiltrated. In case 1 and 2, myxoid change of stromal tissue was noted. Also noted were foci of osteoid metaplasia of the stromal layer in case 1. The authors report three cases of inflammatory pseudotumor of the lung, with comparative observation of each case, associated with literature review, with emphasis on the pathogenesis of this rather infrequent lesion. And some reviews were made on differential diagnosis between inflammatory pseudotumor and non-neoplastic or neoplastic lung mass including so called sclerosing hemangioma.
Diagnosis, Differential

Granulocytic sarcoma is a rare localized tumor composed of granulocytic precusor cells. Granu-locytic sarcoma occurs in a variety of clinical conditions and it is often misdiagnosed histologically. Differential diagnosis frorh lymphoma or nonhematopoietic malignancies such as undifferentiated carcinoma or sarcoma is difficult in the routing histologic examination. An evaluation of clinical and histopathologic features was done on 4 cases of granulocytic sarcoma which were diagnosed at Pusan Paik Hospital from 1988 to 1992. During the period, 282 cases of myelogenous leukemia were diagnosed. Immunohistochemical reaction for lysozyme, myelopero-xidase, leukocyte common antigen, epthelial membrane antigen and cytokeratin was assessed comparing to lymphoma and undifferentiated carcinoma. The histologic features of the granulocytic sarcoma revealed thin nuclear membrane, fine chromatin pattern and one or two small nucleoli. It also often involved the vascular wall and infiltrated the native structures without destruction. Immunohistochemical stain revealed that all(4 cases) of granulocytic sarcoma showed diffuse and strong positivity for myeloperoxidase, and partial but strong positivity for lysozyme. One case of granulocytic sarcoma was negative and 3 cases revealed focal positive reaction for LCA, and all 4 cases was negative for cytokeratin and EMA. In summary, careful observation under light microscopy with immunohistochemical stain for myeloperoxidase, lysozyme, and LCA is helpful in the differential diagnosis of granulocytic sarcoma from malignant lymphoma and cytokeratin and EMA is useful for differential diagnosis from undifferentiated carcinoma.
Diagnosis, Differential

No abstract available.
Diagnosis, Differential*

No abstract available.
Diagnosis, Differential*

Lymphoid lesions of the orbit and conjunctiva may be divided histologically into three groups: monomorphous and cytologically atypical malignant lymphomas, benign reactive follicular hyperplasia or inflammatory pseudotumor, and borderline lymphoid lesions mainly composed of small, non-atypical lymphocytes with or without evidence of plasmacytic differentiation or germinal centers which are difficult to clarify its nature by histologic criteria alone. From 1984 to 1992 at Seoul National University Hospital, 20 cases of orbital lymphoid infiltrates were reviewed to find out histopathologic characteristics of malignant lymphomas and try to classify them properly. Also, we sought histologic findings helpful for differential diagnosis between malignant and borderline cases. Histologic examination of malignant lesions usually revealed the features of low-grade B cell lymphomas of mucosa-associated lymphoid tissue(MALT) origin, which predominantly consist of centrocyte-like(CCL) cells. Among 13 primary orbital lymphomas, six cases were classified as MALT lymphomas of Isaacson, six were more apt to be the type of immunocytoma by kiel classification, and remaining one showed mixed pattern of both types in areas. The one case of malignant lymphoma with diffuse large cell type was confirmed by secondary involvement of intestinal lymphoma. Five cases were confirmed by immunoglobulin k-light chain monoclonality on flow cytometry and immunofluorescence study. The histologic findings such as Dutcher bodies, hemosiderin, deposits and polykaryocytes tended to be more frequently encountered in malignant lymphoma rather than indeterminate lesions and were thought to be helpful ones in making differential diagnosis between malignant and benign lesions. With above findings, we assume that the principal neoplastic cells in the low grade lymphoma arising in the orbit and conjunctiva are CCL cells, which might be originated from the localized memory B cells, and also several kinds of B lymphocytes in on-going differentiation stages such as medium-sized monocytoid B cell, lymphoplasmacytoid cell, plasma cell, and mature small lymphocyte also contribute to the tumor progression.
Diagnosis, Differential