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

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

No abstract available.
Diagnosis, Differential*

Although a great deal has been written about porencephaly during the past 100 years, there is much that remains obscure. The clinical recognition of porencephaly is important because it occurs with sufficient frequency to require consideration in the differential diagnosis of focal cerebral lesions. The authors considered and discussed to fulfill the pathogensis for this case.
Diagnosis, Differential

The differential diagnosis between Spitz nevus and malignant melanoma is difficult due to similar histologic findings. To obtain the useful aids for the differential diagnosis between two diseases, we studied 13 cases of Spitz nevus, 8 benign nevi of compound and intradermal, and 9 melanomas of primary and metastatic, using the immunohistochemical stain for S-100 protein, HMB.45 and proliferating cell nuclear antigen(PCNA). The staining pattern and intensity of S-100 protein showed homogenously strong positive reactivity in all cases. The frequency of HMB.45 positive cell in Spitz nevus was significantly lower than that in melanoma. When compared with the usual compound and intradermal nevi, Spitz nevi showed more significantly positive reaction in the dermal component of nevus cells. The expression of PCNA was higher in melanoma than in Spitz nevus. The immunohistochemical stains for HMB.45 and PCNA are considered as a useful methods for differentiation between Spitz nevus and melanoma, while stain for S-100 protein is not helpful.
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

Cutaneous focal mucinosis was first described by Johnson and Helwig in 1961 and is histo logically characterized by localized accumulation of mucin in the upper and middermis with scattered spindle-shaped fibroblasts. The mucin is jelly-like acid mucopolysaccharide consisting of hyaluronic acid bound to small amounts of chondroitin sulfate and heparin. The pathogenesis of cutaneous mucinosis is unclear. However, studies of various cutaneous mucinoses suggest that there may be an unknown circulating factor that stimulates fibroblasts to produce this material. Differential diagnoses include papular mucinosis, myxoid cyst, cutaneous myxoma. Simple surgical excision is the treatment of choice. In the present case, cutaneous focal mucinosis occurs on the nail bed with onycho mycosis.
Diagnosis, Differential

BACKGROUND: The clinical distinction between herpes simplex virus (HSV) and varicella-zoster virus(VZV) skin infections is sometimes difficult. Potentially, immunohistochemical method can distinguish HSV from VZV infection. However, immunohistochemical studies for the differentiation between them have rarely been reported. OBJECTIVE: The purpose is to investigate the usefulness of immunohistochemical staining in differentiation between HSV and VZV infections. METHODS: We studied 9 cases of herpes zoster, 4 cases of chicken pox, and 5 cases of herpes simplex with monoclonal antibody to VZV. Routine histopathologic findings of the cases were also evaluated. RESULTS: All cases of VZV infections stained with antibody to VZV, but none of HSV infection stained. In VZV infection, 25% of the cases showed strong or diffuse positive reaction, whereas the rest of them showed weak or focal pattern. Histopathologically, the degree of inflammation was significantly greater in HSV infection than in VZV infection. However, vaculitis was more frequently found in VZV infection than in HSV infection. CONCLUSION: We think immunohistochemistry with antibody to VZV is very useful in the differentiation between HSV and VZV infections, even if the reaction pattern may be so weak or focal, as careful interpretation is necessary.
Diagnosis, Differential