|Year : 2013 | Volume
| Issue : 2 | Page : 299-301
Pelvic periprostatic symplastic leiomyoma: An unusual case necessitating a radical surgery
Komal Kathuria1, Santosh Menon1, Kedar Deodhar1, Ganesh Bakshi2, Sangeeta Desai1
1 Department of Pathology, Tata Memorial Hospital, Parel, Mumbai, India
2 Department of Urologic Oncology, Tata Memorial Hospital, Parel, Mumbai, India
|Date of Web Publication||13-Jun-2013|
Department of Pathology, 8th Floor, Annexe Building, Tata Memorial Hospital, Dr. Ernest Borges Marg, Parel, Mumbai - 400 012
Source of Support: None, Conflict of Interest: None
Most pelvic smooth muscle tumors are believed to be malignant, leiomyomas are extremely rare; more so in male patients. Very few cases of symplastic leiomyomas have been described in males. We report an extremely unusual case of a soft tissue mass of periprostatic and periseminal vesicle region in a young adult, which necessitated a radical surgery. Histologically, tumor comprised of smooth muscle bundles with numerous bizarre tumor cells which were immunoreactive with smooth muscle actin (SMA), desmin and h-caldesmon. The diagnostic and treatment dilemmas of these unusual tumors are discussed.
Keywords: Leiomyoma, male, pelvic, symplastic
|How to cite this article:|
Kathuria K, Menon S, Deodhar K, Bakshi G, Desai S. Pelvic periprostatic symplastic leiomyoma: An unusual case necessitating a radical surgery. J Can Res Ther 2013;9:299-301
|How to cite this URL:|
Kathuria K, Menon S, Deodhar K, Bakshi G, Desai S. Pelvic periprostatic symplastic leiomyoma: An unusual case necessitating a radical surgery. J Can Res Ther [serial online] 2013 [cited 2020 Feb 28];9:299-301. Available from: http://www.cancerjournal.net/text.asp?2013/9/2/299/113397
| > Introduction|| |
Leiomyomas are extremely common in females in the uterus and adjacent structures. They are however, uncommon in males, the genitourinary tract (prostate, urinary bladder, scrotum and penis) being one of the commonest sites.  Pelvic leiomyomas are rare, more so in the males.
Symplastic leiomyomas are defined as leiomyomas with atypical large cells containing pleomorphic nuclei and little or no mitotic activity.  Symplastic leiomyomas have essentially been described in the uterus and show a benign follow up after excision.  It is essential to differentiate between symplastic leiomyoma and leiomyosarcoma as both show marked nuclear atypia but their clinical behavior and management differ markedly.
| > Case Report|| |
A 43-year-old male presented with complaints of burning micturition since 1 month. On per rectal examination, a hard nodular mass was felt anteriorly to the rectum, not separate from the prostate. A computerized tomography (CT scan) was performed to delineate the extent of the mass lesion. CT scan revealed a 7 X 7 X 6 cm mass lesion in the rectovesical region, not seen separately from the prostate gland and base of bladder and was presumed to be a soft tissue sarcoma possibly arising from the prostate. The mass also appeared to closely apposed to rectal wall. There was no pelvic or retroperitoneal lymphadenopathy. Chest X-ray and serum PSA levels (0.93 ng/ml) were within normal limits.
A biopsy was performed from the retroperitoneal mass, which revealed a spindle cell neoplasm.Nuclear atypia was pronounced focally even in core biopsy sample. There was no mitosis and necrosis. On immunohistochemistry, the cells were positive for SMA, h-caldesmon and desmin (confirming the smooth muscle origin). They were negative for c-kit and CD34, thereby ruling out a gastrointestinal stromal tumor (GIST). In view of these findings, and limited nature of the biopsy material, a diagnosis of leiomyoma/ low grade leiomyosarcoma was suggested.
In view of the radiological findings of a large sized mass possibly arising from the prostate and a probable histological diagnosis of low grade leiomyosarcoma, an exploration and excision of mass was planned. Intraoperatively mass was adherent to the prostate and base of urinary bladder and hence a cystoprostatectomy was performed, with proper consent of the patient's relatives. Grossly, the tumor appeared to be circumscribed and cut section was solid with vague nodularity and punctate hemorrhages. [Figure 1] The tumor was in close apposition to the musculature of seminal vesicle and prostate but did not infiltrate them. Histology revealed a spindle cell neoplasm arranged in fascicles, showing marked nuclear atypia. The chromatin was smudged rather than hyperchromatic and nucleoli were absent [Figure 2] a-c. However, even after extensive sampling, there was no necrosis and mitotic activity was <1/10hpf. On immunohistochemistry, the spindle tumor cells expressed smooth muscle actin [Figure 2]d and h-caldesmon. The marker, discovered on GIST-1 (DOG-1) and c-kit were done to rule out a gastrointestinal stromal tumor, and were found to be negative in the tumor. Mib-1 immunohistochemistry marked the proliferating cells which were less than 2% (Mib-1<2%) In view of marked nuclear atypia and absence of mitosis and coagulative tumor necrosis, a diagnosis of symplastic leiomyoma was made and the patient was advised a close follow-up.
|Figure 1: Gross appearance of the pelvic symplastic leiomyoma. Cut section showing solid tumor with vague nodularity and punctuate hemorrhages.|
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|Figure 2: The spindle tumor (thick arrow) is seen in close apposition to the prostate gland (thin arrow) but not infiltrating it (Figure 2a, H and E, magnification x 40). The spindle cells of symplastic leiomyoma demonstrating marked nuclear atypia. (Figure 2b and c, H and E, agnification x 100) with smudged and bizarre nuclei (Figure 2c, inset,) Spindle tumor cells immunoreactive to smooth muscle actin (Figure 2d, indirect immunoperoxidase, x 100)|
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| > Discussion|| |
Leiomyomas are rare neoplasms in males, the common sites being the prostate and urinary bladder. Symplastic leiomyomas are even rarer and few cases have been described in the prostate  and scrotum. Pelvic leiomyomas are rare in males and their incidence has been described as 0.5 - 1.2% only, among all retroperitoneal tumors.  Owing to this location, these tumors are labeled as potentially malignant as leiomyosarcomas can have a mitotic index as low as 1/10hpf.  Symplastic leiomyomas have been mostly described in the female genital tract. Downes et al, in the largest series of 24 cases of female genital tract have observed bizarre pleomorphic giant cells in all the cases with a mean mitotic activity of 1.6 mitotic figures/ 10 high power fields (hpf).  On complete follow up, ranging from 1-18.9 years, none of these patients developed recurrence or metastases.
The behavior of these tumors is uncertain especially in male patients. In a study of 10 cases of prostatic leiomyoma with atypia, four cases had recurrence on follow-up ranging from 3 to 16 years.  However, these were believed to be persistent lesions rather than recurrence because no definitive treatment was given in 2 cases and incomplete removal of the lesion was done after the initial diagnosis in 2 other cases. There was no evidence of sarcomatous transformation.
In a large study of 56 cases of retroperitoneal leiomyomas, the tumors which lacked necrosis and had mitotic count <3/50 hpf behaved in a benign fashion on long term follow-up  They also observed that tumors which were classified as leiomyosarcomas on the basis of cellular atypia but mitotic count <3/50 hpf, behaved in a less aggressive manner. In the present case, a long term follow-up has been advised and there is no evidence of recurrence eight months after the surgery.
Morphologically, symplastic leiomyomas are characterized by presence of variable number cells with bizarre nuclei with smudged chromatin and inconspicuous nucleoli. The cells have moderate amount of eosinophilic cytoplasm. However, there should be no mitosis and/or presence of coagulative tumor necrosis. The present case demonstrated all the aforementioned features, thus qualifying for the diagnosis.
The main differential diagnosis in these cases is leiomyosarcoma, which connotes different therapeutic and prognostic implications. Cellular atypia, mitotic activity and/or coagulative tumor necrosis are the criteria used for the diagnosis of leiomyosarcoma. Bizarre pleomorphic tumor cells can be seen in leiomyosarcomas, and a thorough sampling, as was resorted in the present case, is mandatory to assess areas of brisk mitosis and necrosis.
In our case, radiology (CT scan) revealed a mass in the rectovesical region, not seen separate from the prostate. A biopsy was performed, and owing to the presence of spindle tumor cells, some with bizarre nuclei, a diagnosis of leiomyoma/ low grade leiomyosarcoma was suggested. In view of the radiological findings and biopsy diagnosis, a radical cystoprostatectomy had to be performed, as the tumor was adherent to the bladder and prostate.
The other close differential diagnosis which a pathologist needs to bear in mind is an extra gastrointestinal stromal tumors (e-GISTs) which have been reported in the pelvis,  retroperitoneum and mesentery. These tumors may have spindle or epithelioid morphology. Immunohistochemistry for c-kit (CD 117), which is a diagnostic marker for GIST can reliably distinguish between the two.  All leiomyomas are negative for c-kit, while positive for desmin and smooth muscle actin (SMA). It is important to differentiate between the two as targeted therapy (tyrosine kinase inhibitors) is available for GISTs.  C-kit and DOG-1, another marker for GIST were done in our case to categorically rule out the possibility.
In conclusion , pelvic symplastic leiomyomas are extremely uncommon in males. Based on the presence of nuclear atypia, a close follow-up is advised in these patients. However, larger studies need to be done to elucidate the behavior of these tumors.
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[Figure 1], [Figure 2]