0022-534 7/79 / 1226-0841$02.00/0 Vol. 122, December
THE JOURNAL OF UROLOGY
Copyright© 1979 by The Williams & Wilkins Co.
Printed in U.S.A.
FATTY METAPLASIA IN A POSTPUBERTAL UNDESCENDED TESTIS: A CASE REPORT L. H. HONORE* From the Department of Laboratories, Grace General Hospital and Division of Pathology, Memorial University of Newfoundland, Newfoundland, Canada
ABSTRACT
The first case of intratesticular fatty metaplasia in a postpubertal undescended testis is presented. Its differential diagnosis and etiology are discussed briefly. A review of the relevant literature on the morphology of the scrotal1-4 and undescended5- 11 human testis has failed to reveal any mention of fatty metaplasia involving the intertubular connective tissue. In contrast, such a phenomenon, although uncommon, has been described in the ovary. 12 The first case of intratesticular fatty metaplasia is reported herein. CASE REPORT
A healthy, non-obese 37-year-old white man, who had fathered 3 children, was evaluated for a vasectomy. Examination revealed a mid inguinal undescended testis on the right side. The excised testis, measuring 3 X 1.5 X 1 cm. with its coverings,
fatty metaplasia (part A of figure). These metaplastic cells, which were much larger than the adjacent Leydig cells, closely resembled mature adipocytes (part B of figure) with an empty cytoplasm, a thin distinct cell border, a flattened eccentric nucleus and pericellular reticulin. No transition was found between these fat cells and the adjoining Leydig cells. Since the entire testis had been embedded in paraffin no fat stains or ultrastructural studies could be done. DISCUSSION
On the basis of light microscopy this case constitutes a bona fide example of fatty metaplasia involving the intertubular
A, nodule of hyperplastic Leydig cells with microfocus of benign fatty metaplasia. Note nearby tubules with absent spermatogenesis and hyalinization. Masson trichrome, reduced from X210. B, fat cells and adjacent Leydig cells with no transitional stages. Note empty cytoplasm, thin distinct cell borders and eccentric nuclei. H & E, reduced from X890.
was smooth, soft and uniformly atrophic with a homogeneous orange-yellow color on section. After fixation in Bouin's fluid the entire testis was processed for histology. The typical features of postpubertal cryptorchidism were seen microscopically, that is widespread tubular atrophy with variable tunical sclerosis or complete hyalinization, absent spermiogenesis and patchy minimal spermatogenesis, extensive diffuse and nodular Leydig cell hyperplasia and moderate arteriosclerosis. There was 1 subcapsular nodule of non-encapsulated microfocus of
connective tissue of the testis. Unfortunately, because of its unexpected occurrence, further documentation by histochemistry and electron microscopy was not possible. Histologically, the differential diagnosis includes fatty degeneration of Leydig cells and the early stage of a sclerosing lipogranuloma. Fatty degeneration of Leydig cells, which is common in postpubertal cryptorchidism, 11 has a distinctive morphology and evolution. These Leydig cells, which closely resemble adrenocortical cells, become progressively more spongiocytic while the nucleus remains central. At the various stages of degeneration the nucleus shows pyknosis, karyorrhexis and karyolysis and, eventually, the anucleated cell shrinks and disintegrates without causing
Accepted for publication February 2, 1979. * Current address: Department of Pathology, The University of Alberta, Edmonton, Alberta, Canada T6G 2H7. 841
HONORE
842
extracellular lipid spillage or eliciting a foamy histiocyte response. These degenerating Leydig cells never swell to the size attained by the fat cells described herein and they never show the unilocular vacuole in the cytoplasm and the eccentric nucleus. The early stage of a sclerosing lipogranuloma is considered because this lesion has been described in extratesticular genital tissues 13 and a xanthogranulomatous tumor of the ovary has been reported. 14 However, this differential diagnosis is excluded easily by the absence of tissue necrosis, extracellular lipid spillage and secondary inflammation. Adipocytic differentiation in the lower abdomen and pelvis is extensive but fatty metaplasia is rare within the parenchymal derivatives of the primitive gonadal ridge, including the paramesonephric and mesonephric systems. This is not owing to a complete absence of such a potentiality within these organs, as demonstrated by fatty metaplasia in the ovary 12 and the rare development of predominantly mixed fatty tumors in the female genital tract. 15 It is noteworthy that although testicular lipoma is mentioned in 1 monograph16 its occurrence is not mentioned by others, 11- 19 while the existence of the ovarian lipoma/liposarcoma has been questioned. 20 Therefore, it appears that local factors prevent the gonadal mesenchyme from undergoing adipocytic transformation and elucidation of these factors may have important biologic and clinical implications. The etiology of the fatty metaplasia in this case is obscure but it is unrelated to obesity or to any inherited or acquired disorders oflipid metabolism. Its occurrence in an undescended testis raises the possibility that it may be yet another reflection of the basic dysgenesis, which is widely considered to underlie the failure of descent. 5- 11 Clearly, more cases are needed to evaluate this possibility and it is hoped that this report will stimulate research into the factors that control adipocytic differentiation within the testis. REFERENCES
1. Sniffen, R. C.: The testis: I. The normal testis. Arch. Path., 50: 259, 1950. 2. Johnsen, S. G.: The mechanisms involved in testicular degeneration in man. Advance of a theory of the pathogenesis in "idiopathic" hypospermatogenesis. Acta Endocr., suppl., 124: 17, 1967.
3. Harbitz, T. B.: Morphometric studies of the seminiferous tubules in elderly men with special reference to the histology of the prostate. An analysis in an autopsy series. Acta Path. Mic.robiol. Scand., 81: 843, 1973. 4. Honore, L. H.: Ageing changes in the human testis: a light-microscopic study. Gerontology, 24: 58, 1978. 5. Sohval, A. R.: The histopathology of cryptorchidism; study based upon comparative histology of retained and scrotal testes from birth to maturity. Amer. J. Med., 16: 346, 1954. 6. Charny, C. W. and Wolgin, W.: Cryptorchism. New York: Paul H. Roeber, Inc., 1957. 7. Mancini, R. E., Rosemberg, E., Cullen, M., Lavieri, J. C., Vilar, 0., Bergada, C. and Andrada, J. A.: Cryptorchid and scrotal human testes: I. Cytological, cytochemical and quantitative studies. J. Clin. Endocr. Metab., 25: 927, 1965. 8. Gothie, S., Canlorbe, P. and Lange, J. C.: Les cryptorchidies: V. Etude histologique, experimentale et clinique du testicule cryptorchide. Ann. Ped., 13: 262, 1966. 9. Sudmann, E.: The undescended testis. A clinical and histologic study. Acta Chir. Scand., 137: 815, 1971. 10. Scorer, G. C. and Farrington, G. H.: Congenital Deformities of Testis and Epididymis. New York: Appleton-Century-Crofts, pp. 58-75, 1972. 11. Honore, L. H.: Postpubertal untreated cryptorchidism. Anatomical relationship between Leydig cells and tubular sclerosis. Urol. Int., 33: 245, 1978. 12. Hart, W. R. and Abell, M. R.: Adipose prosoplasia of ovary. Amer. J. Obst. Gynec., 106: 929, 1970. 13. Arduino, L. J.: Sclerosing lipogranuloma of male genitalia. J. Urol., 82: 155, 1959. 14. Minkowitz, S., Friedman, F. and Henniger, G.: Xanthogranuloma of the ovary. Arch. Path., 80: 209, 1965. 15. Honore, L. H.: Uterine fibrolipoleiomyoma: report of a case with discussion of histogenesis. Amer. J. Obst. Gynec., 132: 635, 1978. 16. Mostofi, F. K. and Price, E. B.: Tumors of the male genital system. In: Atlas of Tumor Pathology. Washington, D. C.: Armed Forces Institute of Pathology, 2nd series, fasc. 8, p. 127, 1973. 17. Willis, R. A.: Pathology of Tumors, 3rd ed. London: Butterworths, pp. 558-588, 1960. 18. Collins, D. H. and Pugh, R. C. B.: The Pathology of Testicular Tumors. London: E & S Livingstone, 1965. 19. Evans, R. W.: Histological Appearances of Tumours, 2nd ed. Edinburgh: Churchill Livingstone, pp. 605-646, 1966. 20. Fox, H. and Langley, F. A.: Tumours of the Ovary. London: William Heineman Medical Books Ltd., p. 281, 1976.
THE JOURNAL OF UROLOGY
Copyright© 1979 by The Williams & Wilkins Co.
Printed in U.S.A.
FATTY METAPLASIA IN A POSTPUBERTAL UNDESCENDED TESTIS: A CASE REPORT L. H. HONORE* From the Department of Laboratories, Grace General Hospital and Division of Pathology, Memorial University of Newfoundland, Newfoundland, Canada
ABSTRACT
The first case of intratesticular fatty metaplasia in a postpubertal undescended testis is presented. Its differential diagnosis and etiology are discussed briefly. A review of the relevant literature on the morphology of the scrotal1-4 and undescended5- 11 human testis has failed to reveal any mention of fatty metaplasia involving the intertubular connective tissue. In contrast, such a phenomenon, although uncommon, has been described in the ovary. 12 The first case of intratesticular fatty metaplasia is reported herein. CASE REPORT
A healthy, non-obese 37-year-old white man, who had fathered 3 children, was evaluated for a vasectomy. Examination revealed a mid inguinal undescended testis on the right side. The excised testis, measuring 3 X 1.5 X 1 cm. with its coverings,
fatty metaplasia (part A of figure). These metaplastic cells, which were much larger than the adjacent Leydig cells, closely resembled mature adipocytes (part B of figure) with an empty cytoplasm, a thin distinct cell border, a flattened eccentric nucleus and pericellular reticulin. No transition was found between these fat cells and the adjoining Leydig cells. Since the entire testis had been embedded in paraffin no fat stains or ultrastructural studies could be done. DISCUSSION
On the basis of light microscopy this case constitutes a bona fide example of fatty metaplasia involving the intertubular
A, nodule of hyperplastic Leydig cells with microfocus of benign fatty metaplasia. Note nearby tubules with absent spermatogenesis and hyalinization. Masson trichrome, reduced from X210. B, fat cells and adjacent Leydig cells with no transitional stages. Note empty cytoplasm, thin distinct cell borders and eccentric nuclei. H & E, reduced from X890.
was smooth, soft and uniformly atrophic with a homogeneous orange-yellow color on section. After fixation in Bouin's fluid the entire testis was processed for histology. The typical features of postpubertal cryptorchidism were seen microscopically, that is widespread tubular atrophy with variable tunical sclerosis or complete hyalinization, absent spermiogenesis and patchy minimal spermatogenesis, extensive diffuse and nodular Leydig cell hyperplasia and moderate arteriosclerosis. There was 1 subcapsular nodule of non-encapsulated microfocus of
connective tissue of the testis. Unfortunately, because of its unexpected occurrence, further documentation by histochemistry and electron microscopy was not possible. Histologically, the differential diagnosis includes fatty degeneration of Leydig cells and the early stage of a sclerosing lipogranuloma. Fatty degeneration of Leydig cells, which is common in postpubertal cryptorchidism, 11 has a distinctive morphology and evolution. These Leydig cells, which closely resemble adrenocortical cells, become progressively more spongiocytic while the nucleus remains central. At the various stages of degeneration the nucleus shows pyknosis, karyorrhexis and karyolysis and, eventually, the anucleated cell shrinks and disintegrates without causing
Accepted for publication February 2, 1979. * Current address: Department of Pathology, The University of Alberta, Edmonton, Alberta, Canada T6G 2H7. 841
HONORE
842
extracellular lipid spillage or eliciting a foamy histiocyte response. These degenerating Leydig cells never swell to the size attained by the fat cells described herein and they never show the unilocular vacuole in the cytoplasm and the eccentric nucleus. The early stage of a sclerosing lipogranuloma is considered because this lesion has been described in extratesticular genital tissues 13 and a xanthogranulomatous tumor of the ovary has been reported. 14 However, this differential diagnosis is excluded easily by the absence of tissue necrosis, extracellular lipid spillage and secondary inflammation. Adipocytic differentiation in the lower abdomen and pelvis is extensive but fatty metaplasia is rare within the parenchymal derivatives of the primitive gonadal ridge, including the paramesonephric and mesonephric systems. This is not owing to a complete absence of such a potentiality within these organs, as demonstrated by fatty metaplasia in the ovary 12 and the rare development of predominantly mixed fatty tumors in the female genital tract. 15 It is noteworthy that although testicular lipoma is mentioned in 1 monograph16 its occurrence is not mentioned by others, 11- 19 while the existence of the ovarian lipoma/liposarcoma has been questioned. 20 Therefore, it appears that local factors prevent the gonadal mesenchyme from undergoing adipocytic transformation and elucidation of these factors may have important biologic and clinical implications. The etiology of the fatty metaplasia in this case is obscure but it is unrelated to obesity or to any inherited or acquired disorders oflipid metabolism. Its occurrence in an undescended testis raises the possibility that it may be yet another reflection of the basic dysgenesis, which is widely considered to underlie the failure of descent. 5- 11 Clearly, more cases are needed to evaluate this possibility and it is hoped that this report will stimulate research into the factors that control adipocytic differentiation within the testis. REFERENCES
1. Sniffen, R. C.: The testis: I. The normal testis. Arch. Path., 50: 259, 1950. 2. Johnsen, S. G.: The mechanisms involved in testicular degeneration in man. Advance of a theory of the pathogenesis in "idiopathic" hypospermatogenesis. Acta Endocr., suppl., 124: 17, 1967.
3. Harbitz, T. B.: Morphometric studies of the seminiferous tubules in elderly men with special reference to the histology of the prostate. An analysis in an autopsy series. Acta Path. Mic.robiol. Scand., 81: 843, 1973. 4. Honore, L. H.: Ageing changes in the human testis: a light-microscopic study. Gerontology, 24: 58, 1978. 5. Sohval, A. R.: The histopathology of cryptorchidism; study based upon comparative histology of retained and scrotal testes from birth to maturity. Amer. J. Med., 16: 346, 1954. 6. Charny, C. W. and Wolgin, W.: Cryptorchism. New York: Paul H. Roeber, Inc., 1957. 7. Mancini, R. E., Rosemberg, E., Cullen, M., Lavieri, J. C., Vilar, 0., Bergada, C. and Andrada, J. A.: Cryptorchid and scrotal human testes: I. Cytological, cytochemical and quantitative studies. J. Clin. Endocr. Metab., 25: 927, 1965. 8. Gothie, S., Canlorbe, P. and Lange, J. C.: Les cryptorchidies: V. Etude histologique, experimentale et clinique du testicule cryptorchide. Ann. Ped., 13: 262, 1966. 9. Sudmann, E.: The undescended testis. A clinical and histologic study. Acta Chir. Scand., 137: 815, 1971. 10. Scorer, G. C. and Farrington, G. H.: Congenital Deformities of Testis and Epididymis. New York: Appleton-Century-Crofts, pp. 58-75, 1972. 11. Honore, L. H.: Postpubertal untreated cryptorchidism. Anatomical relationship between Leydig cells and tubular sclerosis. Urol. Int., 33: 245, 1978. 12. Hart, W. R. and Abell, M. R.: Adipose prosoplasia of ovary. Amer. J. Obst. Gynec., 106: 929, 1970. 13. Arduino, L. J.: Sclerosing lipogranuloma of male genitalia. J. Urol., 82: 155, 1959. 14. Minkowitz, S., Friedman, F. and Henniger, G.: Xanthogranuloma of the ovary. Arch. Path., 80: 209, 1965. 15. Honore, L. H.: Uterine fibrolipoleiomyoma: report of a case with discussion of histogenesis. Amer. J. Obst. Gynec., 132: 635, 1978. 16. Mostofi, F. K. and Price, E. B.: Tumors of the male genital system. In: Atlas of Tumor Pathology. Washington, D. C.: Armed Forces Institute of Pathology, 2nd series, fasc. 8, p. 127, 1973. 17. Willis, R. A.: Pathology of Tumors, 3rd ed. London: Butterworths, pp. 558-588, 1960. 18. Collins, D. H. and Pugh, R. C. B.: The Pathology of Testicular Tumors. London: E & S Livingstone, 1965. 19. Evans, R. W.: Histological Appearances of Tumours, 2nd ed. Edinburgh: Churchill Livingstone, pp. 605-646, 1966. 20. Fox, H. and Langley, F. A.: Tumours of the Ovary. London: William Heineman Medical Books Ltd., p. 281, 1976.
