THE ULTRASTRUCTURE OF AN INTERSTITIAL-CELL NEOPLASM O F TESTIS THAT PRODUCED LARGE AMOUNTS O F GROUND- SUBSTANCE

IAN CARR Department of Pathology, University and Weston Park Hospital,

Shefield

PLATES CXIX-CXXI

A NEOPLASM is divided into two components, the neoplastic cells proper and the stroma or framework in which they grow. The stroma is composed of various types of connective tissue that contains cells, intercellular substance, and blood and lymphatic vessels. It is generally held to be largely a product of host connective tissue. The present report describes the manner in which, in contrast with the above view, the intercellular matrix in an un- common testicular neoplasm was produced by the neoplastic cells themselves.

MATERIALS AND METHODS

The neoplasm was removed from a man of 21 yr who complained of swelling of the testis that gradually increased in size over a period of 2 yr. There was no complaint of change in sexual function or gynaecomastia. Pre-operative hormone assay was not carried out.

The lesion was an apparently encapsulated mass 4 cm in diameter lying within the testis. On section it had a finely cystic appearance.

Material was fixed in 4 per cent. neutral formaldehyde, embedded in paraffin wax and sectioned at 6 pm. It was stained by the following techniques: haematoxylin and eosin, periodic acid-Schiff, alcian blue, colloidal iron, and toluidine blue (Pearse, 1969). Frozen sections were stained with sudan IV. Further material was fixed in 3 per cent. buffered glutaraldehyde, postfixed in 2 per cent. osmium tetroxide, embedded in Araldite, sectioned, stained with lead citrate and examined in an electron microscope. Some material was stained with ruthenium red by the technique of Luft (1966).

RESULTS The neoplasm was divided by fibrous septa into lobules, some with central degeneration.

The component cells were eosinophilic, and arranged in cords or small clusters. There was considerable cellular pleomorphism but little nuclear atypia. Mitoses were rather uncommon. The cells were rich in RNA and contained some sudanophilic lipid. The interstitial matrix was present in large amounts in some areas and was rich in acid muco- polysaccharide. There was limited invasion of the capsule, but not of epididymis or spermatic cord.

The appearances over-all were those of a rather atypical interstitial-cell neoplasm. The component cells as seen with the electron microscope were arranged in groups of

three or four held together by interdigitation of adjacent membranes, and by desmosomes (figs. 1 and 2). The notable features of the ultrastructure were the presence of large ovoid mitochondria such as were seen in steroid-producing cells (fig. 2), of moderate numbers of lipid globules, of whorls of smooth membrane (fig. 3) and of whorls of rough granular endoplasmic reticulum or Nebenkern (Rasmussen, 1928). These features resembled those of testicular interstitial cells (Carr and Carr, 1962).

The neoplastic cells had a prominent basement-membrane composed of structureless

Received 10 Sept. 1971 ; accepted 5 Nov. 1971. J. PATH.-VOL. 107 (1972) 223

224 IAN CARR

electron-dense material. Between the cells lay irregular strands and bands of this material, which gave the appearance of having been delaminated from the cell surface (fig. 4). This material was best seen after ruthenium red staining. At high magnification some areas showed a fibrillar appearance, with fibrils 10-20 nm in diameter (fig. 3, or with small granules. A few micropinocytic vesicles at the edge of the cells contained similar material (fig. 6).

The results of histochemical examination of paraffin sections showed that the inter- cellular material stained slightly by the PAS technique, and strongly by alcian blue and colloidal iron techniques. The latter reactions were blocked by methylation and slightly increased by saponification. The material was digested by incubation in hyaluronidase for 1 hr at 37°C.

DISCUSSION The general ultrastructlvre of the cells of this neoplasm resembled that of normal inter-

stitial cells, particularly in the presence of membranous whorls (Carr and Carr, 1962) and of Nebenkern (Rasmussen, 1928). The cells did not resemble Sertoli cells (see Carr, Clegg and Meek, 1968). Additional evidence of the origin of this neoplasm was the similarity between the histochemistry of the neoplastic cells and that of the interstitial cells of the adjacent normal testis. The lesion bore considerable ultrastructural resemblance to the interstitial cell lesions described by Beals, Pierce and Schroeder (1964).

The unusual feature of this neoplasm was the amount of acid mucopolysaccharide matrix present in it. Since the matrix was present in large amounts deep in the neoplasm where only neoplastic cells were present, it must be inferred that the neoplastic cells produced the matrix. Small pinocytic vesicles at the edge of the cells were filled with the ground- substance, but there was no evidence about the direction in which these were moving.

The material immediately next to the cells clearly formed a cell coat similar to that described on a variety of cells (see C a n et al., 1970, for references to recent literature). What was interesting and unusual is that this coat was delaminating to form intercellular ground-substance. It is usually assumed that this is produced by cells; it is rarely so obvious as here that it must be.

SUMMARY The ultrastructure of an interstitial cell neoplasm is described in which large amounts

of mucopolysaccharide ground-substance were apparently produced by the neoplastic cells.

This work was supported by a grant from the University of Shefield Cancer Research Committee and carried out with an electron microscope provided by the Yorkshire Council of the Cancer Research Campaign. I am grateful to Mr S. Westby for technical assistance.

REFERENCES BEALS, T. F., PLERCE, G. B., AND SCHROEDER, C. F. 1964. The ultrastructure of human

testicular tumours. I. Interstitial cell tumours. J. Urol., 93, 64. CARR, I., AND CARR, J. 1962. Membranous whorls in the testicular interstitial cell. Anat.

Rec., 144, 143. CARR, I., CLEGG, E. J., AND MEEK, G. A. 1968. Sertoli cells as phagocytes: an electron

microscopic study. J. Anat., 102, 501. CARR, I., EVERSON, G., RANKIN, A., AND RUTHERFORD, J. 1970. The fine structure of the

cell coat of the peritoneal macrophage and its role in the recognition of foreign material. Z. Zellforsch., 105, 339.

LUFT, J. H. 1966. Fine structure of capillary and endocapillary layer as revealed by ruthenium red. Fedn Proc., 25, 1773.

PEARSE, A. G. E. 1969. Histochemical techniques, London. RASMUSSEN, A. T. 1928. In General cytology, ed. by E. V. Cowdry, Philadelphia, p. 373.

VoI. 107, No. 2, June 1972, was issued on 6.9.72.

CARR PLATE CXIX

ULTRASTRUCTURE OF TUMOUR OF TESTIS

FIG. 1 ,--Survey view of a group of neoplastic cells. Glutaraldehyde-osmium tetroxide-lead citrate (G, OT, LC). x 5600.

FIG. 2.-Detail of neoplastic cell showing FIG. 3.-Detail of neoplastic cell to show numerous spheroidal mitochondria. Adja- membranous whorl. G, OT, LC. x 20,800. cent cells are held together by interdigitations and desmosomes. G, OT, LC. x 14,300.

CARR

ULTRASTRUCTURE OF TUMOUR OF TESTIS

PLATE CXX

FIG. 4.-View of borders of three adjacent neoplastic cells showing continuity of cell coat and inter- stitial matrix. Cell coat material is present in deep invaginations of the cell surface. Glutar- aldehyde ruthenium red-osmium tetroxide-lead citrate. (G, RR, OT, LC). x 8000.

CARR PLATE CXXI

ULTRASTRUCTURE OF TUMOUR OF TESTIS

FIG. 5.-Detail of cell coat and interstitial matrix showing fibrillar structure. G, RR, OT, LC. x 20,000.

FIG. 6.--Detail of edge of cell showing continuity of material in micropinocytic vesicle with cell coat, which here is distinctly granular. G, RR. OT, LC. x 50,000.