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

No abstract available.
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

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

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

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

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