Leiomyosarcoma of the prostate. Report of 23 cases

Abstract

Background. Leiomyosarcoma of the prostate is a rare neoplasm that accounts for less than 0.1% of prostate malignancies. Previous reports of this neoplasm consisted of single case studies or small series, often combined with cases of rhabdomyosarcoma. The relationship of prognosis with histologic and immunohistochemical findings has not, to the authors' knowledge, been described in a large series of cases, and the efficacy of various treatments is uncertain. Methods. The authors undertook a clinicopathologic study of all cases of prostate leiomyosarcoma observed at their institution from 1929 to 1994. Twenty‐three cases were retrieved from the files of the Department of Pathology, Mayo Clinic (Rochester, MN), and clinical follow‐up was available for 14. Immunohistochemical studies, including actin, desmin, S‐100 protein, keratin, and vimentin were performed for 18 cases. Results. Patients ranged in age from 41 to 78 years, with a mean of 61 years. Presenting symptoms included urinary obstruction (100%), perineal pain (25%), burning on ejaculation (7%), and weight loss (7%). The neoplasms ranged from 3.3 to 21 cm (mean, 9 cm) in greatest dimension and were often associated with necrosis. Seven tumors were Grade 2, 10 Grade 3 and 6 Grade 4 (Broders' grading system; scale, 1–4). Mitotic figure counts varied from 2 to 24 per 10 high power fields. Fifteen of 15 (100%) cases were immunoreactive for vimentin, 10 of 16 (63%) were immunoreactive for actin, and 3 of 15 (20%) were weakly reactive for desmin. Keratin expression was observed in 4 of 15 cases (27%), and S‐100 protein was negative in all cases. Treatment varied, and usually included a combination of radiation therapy, chemotherapy, and radical prostatectomy or cystoprostatecomy. Follow‐up ranged from 2 to 72 months, with a mean of 19 months. Ten patients died from tumor 3 to 72 months (mean, 22 months) after diagnosis. Four patients were alive, including three with residual tumor and one without evidence of tumor at 2, 4, 30, and 4.5 months, respectively. Local recurrence occurred in 10 of 11 patients, including 5 who had gross residual tumor present after surgery. Metastases developed up to 40 months after surgery (mean, 10.3 months), and most frequently involved the lungs. Conclusions. These findings indicate that prostate leiomyosarcoma has a varied histologic appearance ranging from spindled cell neoplasm reminiscent of smooth muscle to pleomorphic sarcoma. Epithelioid features may be present. Most tumors are immunoreactive with antibodies to vimentin and actin, and reactivity with antikeratin antibodies does not exclude the diagnosis of leiomyosarcoma. Prostate leiomyosarcoma has a poor prognosis, although the length of survival is variable. Radical surgery was the treatment of choice in the current series, but complete excision was difficult in most cases and did not result in cure.

Utility of ALK-1 protein expression and ALK rearrangements in distinguishing inflammatory myofibroblastic tumor from malignant spindle cell lesions of the urinary bladder

“…However, such a dual expression pattern should also elicit the consideration of a prostatic leiomyosarcoma with extension into the urinary bladder or a primary sarcomatoid urothelial carcinoma with muscle differentiation, as these lesions have been shown to coexpress cytokeratins and myogenic markers as well. 36,37 In summary, we expand the literature with a large series of urinary bladder inflammatory myofibroblastic tumors harboring ALK gene rearrangements, and confirm the utility of immunohistochemical detection of ALK-1 protein and FISH analysis for ALK rearrangements in distinguishing inflammatory myofibroblastic tumor from other malignant spindle cell tumors of the urinary bladder. We suggest both methods of detection should be concomitantly utilized as the percentage of either immunostain or FISH-positive cells is highly variable and a falsenegative result could be easily generated.…”

Spindle cell lesions of the adult prostate

“…Cytokeratin expression is observed in about one-quarter of cases. 17 In addition, some leiomyosarcomas have been reported to express the progesterone receptor, similar to STUMPs and stromal sarcomas. 18 Patients with leiomyosarcoma commonly have a poor outcome, with 50-75% of patients dying from disease within 2-5 years.…”

“…15,16 Lesions may range in size from 3 to 21 cm and are often highly infiltrative. Microscopically, these hypercellular lesions are composed of intersecting bundles of spindled cells with atypia ranging from moderate to severe (Figure 11).…”

Sarcoma of Prostate of Myofibroblastic Origin

“…None of the cases classified as PSS during the analysis of a series of 22 cases by Gaudin et al were positive for HHF-35, SMA or desmin [2]. In a series of 23 cases of leiomyosarcoma, all cases were immunoreactive for vimentin, 63% were immunoreactive for actin, 20% were weakly reactive for desmin and S-100 protein was negative in all cases [4]. For myofibroblastic sarcoma, IHC lesions expressed anaplastic lymphoma kinase (ALK) in 57%, AE 1/3 in 73%, CAM5.2 in 67% , CK18 in 100%, actin in 92%, desmin in 79%, calponin in 86%, caldesmon in 57% and most lacked S100, CD34, CD117, CD21 and CD23 [1].…”