GRANULAR
CELL
NEOPLASM
OF PROBABLE
ANTHONY JAMES
A. EASON,
KAROL,
EDWARD
MYOBLASTOMA:
PERINEAL
NEURAL
ORIGIN
M.D.
M.D.
J. COLLINS,
M.D.
From the Division of Urology, University of California School of Medicine, San Francisco, California
ABSTRACT -A seventy-year-old granular cell myoblastoma densely known perineal neoplasm of neural
man with a painless, perineal neoplasm was found to have a adherent to the b&bar urethra. This case represents the fourth origin. ~___~
Mohr and Peterson’ have recently reported 2 cases of perineal neoplasms of neural origin. Their review of the literature revealed only 34 other cases of perineal tumors, of which one alone was of neural origin.’ We wish to add an unusual case of perineal neoplasm of probable neural origin. Case Report A seventy-year-old man had noted a mass in his perineum approximately one year before his admission to the hospital. The mass had been entirely asymptomatic but had increased slightly in size since first noticed. The patient denied obstructive and irritative voiding symptoms. Physical examination disclosed no remarkable findings except for a 2cm. very firm nodule in the midperineum. This nodule was mobile and nontender to palpation. Results of rectal and prostatic examinations were normal. Laboratory investigation including complete blood count, serologic test for syphilis, and electrolyte, creatinine, and blood urea nitrogen levels disclosed no abnormality. Findings on excretory urography were within normal limits. A retrograde urethrogram showed the bulbar urethra anteriorly displaced over a smooth perineal mass (Fig. 1). Exploratory surgery was done through a midline perineal incision, and an encapsulated firm mass was found to be densely adherent to the bulbar urethra. A frozen section of the
UROLOGY
/
AUGUST 1977
/
VOLUME X. NUMBER 2
FIGURE 1. Retrograde urethrogram shows displacement of bulbar urethra over perineal mass.
tumor was read as granular cell myoblastoma. Consequently, a thin layer of residual tumor was left at the junction of the urethra from which it appeared to have arisen. Because of the benignity of the tumor and the patient’s age, it was considered that urethral resection was not indicated. Postoperatively, the patient voided well and is currently asymptomatic. Gross pathologic examination showed a 5.5Gm., firm, round nodule, 2.5 cm. in diameter. Its outer surface was covered by a thin, pink membrane and the cut surfaces were diffusely pale yellow in color and fibrous in appearance, with a trabecular pattern. Microscopic examination revealed multiple rests of closely packed large cells, with abundant, deeply eosinophilic granular cytoplasm and
159
FIGURE 2. (A) Histologic microphotograph shows nerve fascicles within tumor (original magnijkatiotz x 200). (B) Higher power view shows granular eosinophilic cytoplasm of tumor cells (original magnijcation
x 1,000).
small, oval nuclei. trabecular pattern nests (Fig. 2).
Fibrous septae arranged in a extended between the cell
Comment Granular cell myoblastoma is a rare, benign tumor, usually occurring in the tongue,3 skin, breast, subcutaneous tissue, and miscellaneous other sites. Its origin has long been disputed, and hypotheses have implicated adult skeletal muscle, embryonal muscle rests, histiocytes, fibroblasts, and degenerative changes in muscle and peripheral nerves (Schwann’s cell). Fust and Custer4 favored the concept of neurogenesis of granular cell myoblastomas. Their studies demonstrated concentric masses of granular tumor cells with cores consisting of bundles of axis cylinders and peripheries resembling expanded and frayed nerve sheaths. They also observed granular tumor cells singly and in clumps within the sheaths of nerve twigs at some distance from the tumor proper. Ashburn and Rodger5 found tumor cells in nerve sheaths in 9 of their 12 cases and also noted involvement of nerves near but outside the study of 43 tumor area. Bangle’s 6 histologic tumors demonstrated two patterns of nerve involvement. The most prominent was that of granular cells concentrically arranged in whorls of varying thickness about a core of intact myelinated nerve fibers. The other was that of granular cells within nerve fascicles. The two patterns could be seen singly and together in different portions of the same tumor. By studying serial sections Bangle observed that what appeared to be isolated granular cells actually followed a perineural or intraneural course that eventually became continuous with the main tumor. Mouradian and associates7 reported 1
160
case of granular cell myoblastoma of the bladder and located 5 others in the literature. We have found no other case of this tumor arising from the urethra. Al-Sarraf, Loud, and Vaitkevicius? reported on a more malignant granular cell myoblastoma in which recurrent tumor required treatment with bilateral groin dissections and abdominoperineal resection. We believe that our case represents the more common benign lesion, but clinical follow-up will be necessary to confirm this diagnosis. In conclusion, the origin of granular cell myoblastoma remains disputed. However, a neural origin appears likely. The specific cell type involved - perineural or intraneural fibroblast, Schwann’s cell, histiocyte, vascular or endoperineural endothelial cell remains unknown. Editor, A-644 University of California School of Medicine San Francisco, California 94143 References 1. Mohr S, and Peterson NE: Perineal neoplasms, J. Ural. 114: 752 (1975). 2. Carlson HE: Neurilemmoma of the perineum, ibid. 94: 158 (1965). 3. Collins DA, and Frish J: Diagnosis and management of myoblastoma of the tongue, Natl. Dental Assoc. Q. 19:42 (1961). 4. Fust JA, and Custer RP: On the neurogenesis of socalled granular cell myoblastoma, Am. J. Clin. Pathol. 19: 522 (1949). 5. Ashburn LL, and Rodger RC: Myoblastoma, neural origin: report of six cases, one with multiple tumors, ibid. 22: 440, 1952. 6. Bangle R Jr: A morphological and histochemical study of the granular-cell myoblastoma, Cancer 5: 950 (1952). 7. Mouradian JA, Coleman JW, McGovern JH, and Cray GF: Granular cell tumor (myoblastoma) of the bladder, J. Urol. 112: 343 (1974). 8. Al-Sarraf M, Loud AV, and Vaitkevicius VK: Malignant granular cell tumor, Arch. Pathol. 91: 556 (1971).
UROLOGY
/
AUGUST
1977
/
VOLUME
X, NUMBER
2
CELL
NEOPLASM
OF PROBABLE
ANTHONY JAMES
A. EASON,
KAROL,
EDWARD
MYOBLASTOMA:
PERINEAL
NEURAL
ORIGIN
M.D.
M.D.
J. COLLINS,
M.D.
From the Division of Urology, University of California School of Medicine, San Francisco, California
ABSTRACT -A seventy-year-old granular cell myoblastoma densely known perineal neoplasm of neural
man with a painless, perineal neoplasm was found to have a adherent to the b&bar urethra. This case represents the fourth origin. ~___~
Mohr and Peterson’ have recently reported 2 cases of perineal neoplasms of neural origin. Their review of the literature revealed only 34 other cases of perineal tumors, of which one alone was of neural origin.’ We wish to add an unusual case of perineal neoplasm of probable neural origin. Case Report A seventy-year-old man had noted a mass in his perineum approximately one year before his admission to the hospital. The mass had been entirely asymptomatic but had increased slightly in size since first noticed. The patient denied obstructive and irritative voiding symptoms. Physical examination disclosed no remarkable findings except for a 2cm. very firm nodule in the midperineum. This nodule was mobile and nontender to palpation. Results of rectal and prostatic examinations were normal. Laboratory investigation including complete blood count, serologic test for syphilis, and electrolyte, creatinine, and blood urea nitrogen levels disclosed no abnormality. Findings on excretory urography were within normal limits. A retrograde urethrogram showed the bulbar urethra anteriorly displaced over a smooth perineal mass (Fig. 1). Exploratory surgery was done through a midline perineal incision, and an encapsulated firm mass was found to be densely adherent to the bulbar urethra. A frozen section of the
UROLOGY
/
AUGUST 1977
/
VOLUME X. NUMBER 2
FIGURE 1. Retrograde urethrogram shows displacement of bulbar urethra over perineal mass.
tumor was read as granular cell myoblastoma. Consequently, a thin layer of residual tumor was left at the junction of the urethra from which it appeared to have arisen. Because of the benignity of the tumor and the patient’s age, it was considered that urethral resection was not indicated. Postoperatively, the patient voided well and is currently asymptomatic. Gross pathologic examination showed a 5.5Gm., firm, round nodule, 2.5 cm. in diameter. Its outer surface was covered by a thin, pink membrane and the cut surfaces were diffusely pale yellow in color and fibrous in appearance, with a trabecular pattern. Microscopic examination revealed multiple rests of closely packed large cells, with abundant, deeply eosinophilic granular cytoplasm and
159
FIGURE 2. (A) Histologic microphotograph shows nerve fascicles within tumor (original magnijkatiotz x 200). (B) Higher power view shows granular eosinophilic cytoplasm of tumor cells (original magnijcation
x 1,000).
small, oval nuclei. trabecular pattern nests (Fig. 2).
Fibrous septae arranged in a extended between the cell
Comment Granular cell myoblastoma is a rare, benign tumor, usually occurring in the tongue,3 skin, breast, subcutaneous tissue, and miscellaneous other sites. Its origin has long been disputed, and hypotheses have implicated adult skeletal muscle, embryonal muscle rests, histiocytes, fibroblasts, and degenerative changes in muscle and peripheral nerves (Schwann’s cell). Fust and Custer4 favored the concept of neurogenesis of granular cell myoblastomas. Their studies demonstrated concentric masses of granular tumor cells with cores consisting of bundles of axis cylinders and peripheries resembling expanded and frayed nerve sheaths. They also observed granular tumor cells singly and in clumps within the sheaths of nerve twigs at some distance from the tumor proper. Ashburn and Rodger5 found tumor cells in nerve sheaths in 9 of their 12 cases and also noted involvement of nerves near but outside the study of 43 tumor area. Bangle’s 6 histologic tumors demonstrated two patterns of nerve involvement. The most prominent was that of granular cells concentrically arranged in whorls of varying thickness about a core of intact myelinated nerve fibers. The other was that of granular cells within nerve fascicles. The two patterns could be seen singly and together in different portions of the same tumor. By studying serial sections Bangle observed that what appeared to be isolated granular cells actually followed a perineural or intraneural course that eventually became continuous with the main tumor. Mouradian and associates7 reported 1
160
case of granular cell myoblastoma of the bladder and located 5 others in the literature. We have found no other case of this tumor arising from the urethra. Al-Sarraf, Loud, and Vaitkevicius? reported on a more malignant granular cell myoblastoma in which recurrent tumor required treatment with bilateral groin dissections and abdominoperineal resection. We believe that our case represents the more common benign lesion, but clinical follow-up will be necessary to confirm this diagnosis. In conclusion, the origin of granular cell myoblastoma remains disputed. However, a neural origin appears likely. The specific cell type involved - perineural or intraneural fibroblast, Schwann’s cell, histiocyte, vascular or endoperineural endothelial cell remains unknown. Editor, A-644 University of California School of Medicine San Francisco, California 94143 References 1. Mohr S, and Peterson NE: Perineal neoplasms, J. Ural. 114: 752 (1975). 2. Carlson HE: Neurilemmoma of the perineum, ibid. 94: 158 (1965). 3. Collins DA, and Frish J: Diagnosis and management of myoblastoma of the tongue, Natl. Dental Assoc. Q. 19:42 (1961). 4. Fust JA, and Custer RP: On the neurogenesis of socalled granular cell myoblastoma, Am. J. Clin. Pathol. 19: 522 (1949). 5. Ashburn LL, and Rodger RC: Myoblastoma, neural origin: report of six cases, one with multiple tumors, ibid. 22: 440, 1952. 6. Bangle R Jr: A morphological and histochemical study of the granular-cell myoblastoma, Cancer 5: 950 (1952). 7. Mouradian JA, Coleman JW, McGovern JH, and Cray GF: Granular cell tumor (myoblastoma) of the bladder, J. Urol. 112: 343 (1974). 8. Al-Sarraf M, Loud AV, and Vaitkevicius VK: Malignant granular cell tumor, Arch. Pathol. 91: 556 (1971).
UROLOGY
/
AUGUST
1977
/
VOLUME
X, NUMBER
2
