No abstract

Tumor forming acute promyelocytic leukemia (APL) is rare and only three cases have been documented. However, there are no reports on either the chloromatous character or electron microscopical analysis. The present paper dealt with a light, electron microscopic and histochemical study of the tumor of APL in a 55‐year‐old Japanese male. The tumors found in the anterior mediastinum and right lower extremity. He died from respiratory disturbance and hydrothorax due to obstruction of the pulmonary truncus by the mediastinal tumor. In electron microscopy, the tumor cells showed dilatation, eolloracious pattern and honey‐comb‐like structure of rough endoplasmic reticula (RER) and parallel array‐arrangement of smooth endoplasmic reticula (SER). These abnormalities of ER are the same as those recently recognized in leukemic cells in APL. Furthermore, the intercellular junctions composed of opposing dense patches of the cytoplasmic plasmalemma were frequently found between the more immature tumor cell of the mediastinum.

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A 61-year-old male was found to have multiple cutaneous nodules, four subcutaneous tumors, and diffuse small nodular lesions of both lungs. The biopsy specimen of the skin lesions revealed a proliferation of histiocytic cells containing Langerhans' cell granules (Birbeck granules). Chemotherapy including vincristine, cyclophosphamide (endoxan), 6-mercaptopurine, and prednisolone (VEMP) for ten weeks improved the skin lesions, some of which disappeared. After resection of all the remaining skin lesions, there was no recurrence. This case seems to be a special type of eosinophilic granuloma or multicentric reticulohistiocytosis.

Metabolism of arachidonic acid (AA) by human platelets was studied by TLC. Gelfiltered platelets (GFP) were eluted both with Ca2+-free Tyrode albumin solution (pH 7. 3) and with albumin-free Haslam solution (pH 7.4). GFP was stimulated by different concentrations of thrombin (f.c.: 0.06-5u/ml).