Malignant teratoma of the thyroid gland was found in a 19‐year‐old female. She was given a combined surgical and irradiation treatment. The tumor was 5.0·4.0·3.6 cm and located in the lower right lobe of the thyroid gland. Light and electron microscopical examinations revealed mature or immature derivatives of the three primordial germ layers. The dominant portion of the tumor was composed of numerous masses of cancerous epithelial cells, which were distributed randomly in the mesenchymal tissue. Tumor cells invaded and replaced the surrounding thyroid tissue with occasional tumor thrombi in the lumens of blood vessels. No metastatic tumor was found in the lymph nodes. The patient was given a course of external irradiation, a total dose of 4000 rads, to the right thyroid area. Eight months after surgery, she is well and without any evidence of recurrence or metastasis.
The light and electron microscopic characteristics of an adenofibroma of the rete testis in a 51‐year‐old man are described. The tumor was 5.5 cm in greatest diameter and situated in the anterior superior portion of the right testis. It was composed mainly of mesenchymal and secondary epithelial proliferation. Long slit‐like spaces and short tubules lined by a layer of epithelial cells were seen in the mesenchymal tissue. The epithelium was histochemically and ultrastructurally similar to that of the rete testis, and the tumor was considered to be of rete testis origin. ACTA PATHOL JPN 38: 105–112, 1988.
A case of adenoid cystic carcinoma which developed in the left parotid gland of an 11-year-old girl was studied by electron microscopy. Islands of tumor cells, showing glandular and cribriform appearances, infiltrated the surrounding tissue and nerves. True lumina and pseudocysts were present in the islands of tumor cells. Electron microscopic examination revealed two types of tumor cells; clear cells (secretory epithelial cells) and dark cells myoepithelium-like cells). Some of the tumor cells, showing a transitional form between the two types, formed a part of the luminal wall. There were many crystalline spicules, cellular debris, and fine stellate granules in the lumina. Pseudocysts were composed of replicated basal laminae, fine stellate granules, and a central core of microfilaments. Rarely, a capillary was noted in the center of the pseudocysts. It is speculated that ultrastructural features of adenoid cystic carcinoma in children may differ from the adult cases in the following ways; they contain numerous crystalline spicules in the lumina, dark cells with microvilli forming the luminal wall, and fine capillaries in the pseudocysts. ACTA PATHOL. JPN. 30: 631-638, 1980.
A direct causal relationship between a human DNA virus, adeno serotype 12, and malignant transformation in target cells (sensory retinal neuronal precursors) was suggested by the development of a remarkably uniform retinoblastoma-like neoplasm in rats. In order to focus upon incipient photoreceptor differentiation, 27 3-day-old CD rats were selected for intraocular virus inoculation. A single injection of 0.03 ml of the virus fluid, 104.5 TCID50 HeLa cells/0.1 ml was given in the left eye. Within 73 to 167 days after the virus inoculation, 12 rats (44.4%) developed retinal tumors in the left eye. Although retinal tumors mimicking human retinoblastoma with true rosettes were anticipated, the highly uniform histopathologic appearance of all 12 eyes was virtually indistinguishable from that of 0-day-old rats. However, multiple foci of malignant cells fusing with the inner segment of relatively well-differentiated retinal layers were found haphazardly throughout the cases; such retinal remnants were not detectable in tumors of 0-day-old rats. Electron microscopy revealed poorly differentiated tumor cells that possessed a single cilium consisting of a typical ring of nine doublets with no axial pair (a 9 plus 0 pattern). Advenovirus-specific T-antigens detected in vivo by the immunofluorescein microscopic procedure in abortively infected or transformed cells clearly indicated that some neuronal precursors destined for part of the ganglioneuronic layer are selectively susceptible to viral oncogenesis. No preferential involvement of the photoreceptor cells was observed. No control animals developed retinal neoplasms.
Comparison of ultrastructural features between leiomyosarcoma and leiomyoma of the duodenum was made. There was no absolute difference between the two, but the following ultrastructural features of leiomyosarcoma were different from leiomyoma: (1) occasional conglomerations of mitochondria surrounded by granular endoplasmic reticulum; (2) quite rare presence of single cilia; (3) frequent occurrence of intranuclear inclusion bodies; (4) variability in nuclear size and shape; and (5) wide interstitial space with scanty collagen fibrils. Although both tumors were considered to be of smooth muscle origin, their ultrastructural features were distinctively different from the normal smooth muscle in some points. In addition to the light microscopic findings, ultrastructural features were considered to be valuable for distinguishing the malignant from the benign smooth muscle tumors in the gastrointestinal tract.
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