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LUNG CANCER METASTASIS TO ADRENAL CORTICAL ADENOMAS

WILSON I. B. ONUIGBO Department of Pathology, General Hospital, Enugu, Nigeria

THAT malignant tumours may spread to benign tumours has been known for over a century (Vogel, 1847; Paget, 1853), though De Morgan (1874) emphasised that most such benign tumours were not invaded even in cases in which numerous metastases were present elsewhere.

Metastases seem to be especially frequent in adrenal cortical adenomas (Rol- leston, 1936; Willis, 1952; Spencer, 1954; Cussen, 1960; Cutler, 1962).

It appears to be especially common in oat-cell carcinoma of the lung, but I have not been able to find a systematic study devoted to its occurrence.

MATERIAL AND METHOD

During a country-wide survey of the necropsy records of 27 British Medical Schools and seven associated hospitals, 7125 cases of lung cancer were collected. It was noted that there were 18 cases (at 14 centres) in which the metastases in the adrenal gland were stated to be situated in cortical adenomas. Unstained sections of adrenal tissue from these cases were later requested from the various centres: materials from five cases were not available for personal study and in a further case no adenoma was discernible. Sections from two cases mentioned in recent papers (Cussen; Billinghurst et al., 1961) were also procured. A further example occurred in my own post-mortem series of 113 lung cancers. This paper is thus based on a total of 15 cases. The histological assessment was made in each case on haematoxylin-and-eosin-stained sections of paraffin-embedded, formalin-fixed adrenal tissue.

RESULTS

The most striking finding was the cell type of the tumours: 12 of the 15 were of the oat-cell variety. There was one case each of adenocarcinoma, squamous-cell carcinoma, and polygonal-cell carcinoma (classification of Walter and Pryce, 1955).

Adenomas were present in both adrenal glands in 5 cases: in two the adenomas on both sides exhibited secondary deposits, but in three the deposits were one-sided. Of the remaining 10 cases, although the adenomas were present unilaterally, six displayed metastases not only in the adenomas but also in the apparently normal parenchyma of the opposite gland, and the remaining four showed metastases limited to the adenomatous gland.

In 8 cases tumour cells were found within the thick-walled central vein or its tributaries. In these cases tumour masses sometimes abutted on or infiltrated into the vessel wall. Occasionally, veins not contiguous to the metastatic deposits also revealed clumps of tumour cells. More commonly, the cortical sinusoids and capillary vessels near the established deposits were filled with blood and the invading cells together.

Lymphatic infiltration was difficult to assess, except in the periadrenal fatty areolar tissue, and, in most sections only tags of such tissue remained. However, in three cases perivascular lymph vessels laden with tumour cells were easily recognisable. Another case showed diffuse infiltration of both the fatty areolar tissue and the capsule of the gland. Bullock and Hirst’s (1953) observation that vessels of capillary dimensions in the parenchyma frequently contained tumour cells but no red blood corpuscles was confirmed. It was uncertain whether these vessels were lymphatic or not. Karsner (1950) and others do not mention the existence of lymphatic vessels in adrenal adenomas; this is a field that calls for research.

DISCUSSION

Cunningham (1958) wrote that the tendency of oat-cell carcinoma to metastasise in the adrenals remains unexplained. I suggest that this may in part depend on the frequency with which oat-cell carcinomas spread to adenomas of the cortex of this organ. Such adenomas are of frequent occurrence and are often quite small. It is not unlikely that, when they are overrun by the invading cells, they are com- pletely obliterated. Serial sections of cortical adenomas may reveal earlier micro- scopic metastases in this type of lung cancer. It is hoped to verify this by means of a prospective series.

It has not been possible in this series to assess the relative roles of blood and lymph in the transportation of the tumour cells to the adenomas. The case that I examined post mortem showed the metastatic patterns that, in my view (Onuigbo, 1961a and b), are suggestive of the premier role of the lymphatics in adrenal in- vasion.

SUMMARY

Fifteen cases of lung cancer metastasising to cortical adenomas of the adrenal gland are presented.

Twelve were oat-celled. The high frequency of metastasis to the adrenal gland may be partly explained by the suitability of the soil of cortical adenomas for the growth of the oat-cell carcinoma.

I am greatly indebted to my former Chief, Professor D. F. Cappell, for facilities to carry out this work at the University of Glasgow, and to Drs B. Lennox and A. T. Sandison for their interest. Dr J. F. Boyd of Ruchill Hospital, Glasgow, gave me the opportunity to perform the necropsy on one case. For facilitating the histo- logical study of the other cases, my thanks are due to Professors R. C. Curran, I. Doniach, C. V. Harrison, K. R. Hill, G. L. Montgomery, D. M. Pryce, G. Payling Wright and J. S. Young, and to Drs L. J. Cussen, W. B. Davis, A. Dick, N. M. Holmes, G. B. D. Scott and A. G. Stansfeld.

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