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 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 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

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

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*

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