Two Cases of Spindle Cell Neoplasms in Patients Undergoing Holmium Laser Enucleation of the Prostate

Abstract

Background: Holmium laser enucleation of the prostate (HoLEP) has proven to be effective in benign proliferations of the prostate resulting in large prostatic volumes. It is a less-invasive surgical alternative to transurethral resection and surgical resection. Prostatic adenocarcinoma can incidentally be found in the enucleated tissue. Occasionally, nonadenocarcinomatous forms of neoplasia occur such as sarcoma.

Case Presentation: Two male patients, both 65 years old, undergo HoLEP for gigantic prostates. The first patient presented with recurrent hematuria and clot retention. After HoLEP, the patient voiding symptoms improved. Pathologic immunostaining of the tissue showed spindle cell proliferation consistent with stromal tumor of uncertain malignant potential (STUMP). The second patient presented with acute urinary retention and subsequently underwent HoLEP. Pathologic examination of the enucleated tissue was consistent with prostatic stromal sarcoma.

Conclusion: HoLEP is a well-established surgical treatment for gigantic proliferations of benign prostatic tissue. Occasionally, patients who are candidates for HoLEP may have a rare underlying pathologic condition such as a sarcoma or a STUMP. Exclusion of underlying malignant processes in massive prostates is necessary before operating.

Introduction and Background

Benign prostatic hyperplasia (BPH) is a common disease with multiple treatment modalities. Holmium laser enucleation of the prostate (HoLEP) is a well-established alternative to transurethral resection as well as open prostatectomy.

Presentation of Case

Case 1

A 65-year-old male patient was transferred to our facility for recurrent gross hematuria and urinary retention from an outside hospital where he was initially hospitalized for alcohol withdrawal. He denied any prior urologic history. Digital rectal examination showed an enlarged smooth prostate without palpable masses. CT scan showed a massively enlarged prostate with a prominent median lobe (Fig. 1). A prostate-specific antigen (PSA) level was not obtained because of the semiurgent nature of his presentation. Owing to ongoing hematuria, recurrent clot retention, and failure of conservative management, the patient was taken to the operating room for HoLEP.

FIG. 1.

CT pelvis from Case 1 showing an enlarged prostate compressing the bladder.

On cystoscopy, the bladder was normal. There was a huge median lobe with varices and smaller lateral lobes. Using a 26F Storz laser resectoscope and sheath and a 550 μm Boston Scientific holmium laser fiber at 40 and 80 W, 254 g of prostate was enucleated in the standard manner. A Wolf Piranha Morcellator was used to morcellate the tissue in two stages. Unlike typical prostate adenoma, the tissue was firm and rubbery, which made morcellation extremely difficult because of the inability of the morcellator to grasp the tissue. The total morcellation time was 350 minutes (170 in the first stage then 180 the second stage), which was performed for a 2-day interval, the reason behind not doing a cystotomy is that the nature of the pathology analysis at this point was not clear.

Immunostaining showed spindle cells (Fig. 2), which are diffusely and strongly positive for smooth muscle actin and desmin, which are muscle markers. Pathology report showed moderate to strong patchy positivity with CD34 and weak to moderate patchy staining with progesterone receptors (PR). The spindle cells were negative for keratin, high molecular weight keratin, and CD117. For this pattern, the differential diagnosis includes benign prostatic stromal hyperplasia and stromal tumor of uncertain malignant potential (STUMP).

FIG. 2.

Microscopic pathology analysis of 65-year-old male patient with differential diagnosis includes benign prostatic stromal hyperplasia and STUMP. This pattern is composed of a cellular proliferation of spindle cells with rare scattered benign glands (20 × )—HoLEP. HoLEP, holmium laser enucleation of the prostate; STUMP, stromal tumor of uncertain malignant potential.

The patient passed a voiding trial and was discharged home on postoperative day 4 without a Foley catheter.

Case 2

A 65-year-old male patient presented with acute urinary retention. Digital rectal examination showed a large smooth prostate without nodularity. His PSA was 0.4 ng/dL 2 months before presentation. He underwent a transrectal ultrasonography that demonstrated a prostate volume of 226 g. BPH was presumed to be the underlying pathology analysis. HoLEP was performed as described earlier in Case 1. During the procedure, the prostate and bladder appeared to be shifted to the right. The usual surgical landmarks and planes were difficult to identify. At one point, an abscess-like cavity was entered during the enucleation with efflux of necrotic material. A cystogram was performed, which confirmed the bladder to be shifted to the right because of extrinsic mass effect. Intraoperatively, the planes were not clear, there was necrotic tissue, and there was uncertainty regarding the underlying pathology analysis. The enucleation of the adenoma was performed without definite identification of the surgical capsule resulting in an under predicted volume of enucleated prostate tissue. Morcellation of 23.9 g of prostatic tissue was performed without difficulty.

Pathologic examination of the enucleated prostatic tissue showed atypical stromal spindle cell proliferation with focal necrosis involving 10% to 15% of the total specimen (Fig. 3A). In addition to the necrosis, the proliferation is hypercellular with cellular atypia and mitotic activity. Immunostaining showed high proliferative index as highlighted with Ki-67. The cells are weakly positive for PR, focally positive for CD34, and negative for CD117 (c-kit) which is a transmembrane protein that functions as a tyrosine kinase receptor, smooth muscle actin, desmin, keratin, BCL-2, and calponin (Fig. 3B). The overall morphology and staining pattern are most consistent with prostatic stromal sarcoma.

FIG. 3.

Microscopic pathology analysis of a 65-year-old man with prostatic stromal sarcoma. (A) Atypical stromal spindle cell proliferation with focal necrosis involving 10% to 15% of the total specimen. In addition to the necrosis, the proliferation is hypercellular with cellular atypia, mitotic activity (20 × )—HoLEP. (B) Desmin detects a protein that is expressed by cells of normal smooth muscle; Desmin is primary located at or near the periphery of cells (40 × )—cystoprostatectomy (prostate). (C) High-grade spindled cell sarcoma with focal rhabdomyoblastic differentiation with osseous matrix formation (20 × )—cystoprostatectomy (prostate).

A CT of the abdomen and pelvis showed a large 11.0 × 13.2 × 12.2 cm mass in the left pelvis (Fig. 4) and also a complex mass measuring 5.3 × 5.6 × 6.3 cm in the right kidney. A percutaneous biopsy was performed on the renal mass, which was consistent with renal cell carcinoma. The patient underwent open synchronous cystoprostatectomy and radical nephrectomy 6 weeks after HoLEP through a midline incision. The kidney, ureter, bladder, and prostate were removed en bloc. Cystoprostatectomy showed high-grade spindled cell sarcoma with focal rhabdomyoblastic differentiation centered in the bladder specifically involving the bladder wall and serosa and invaded into the prostate. Immunostaining showed myogenin negative, desmin positive, and focal myoD1 positive with osseous matrix formation (Fig. 3C).

FIG. 4.

CT pelvis from Case 2 showing an enlarged prostate measuring 11.0 × 13.2 × 12.2 cm.

Discussion and Literature Review

HoLEP is a well-established alternative to transurethral resection of the prostate (TURP) and open prostatectomy for management of BPH of any sized gland. HoLEP consists of enucleation of prostate adenoma using holmium laser followed by morcellation of the enucleated prostatic tissue that remains in the bladder. HoLEP has proved to be an especially effective modality for gigantic prostates (>100 g), such as in the patients we reported.

Incidentally finding cancer is not uncommon when surgically treating BPH. TURP has been shown to inadvertently identify prostatic adenocarcinoma up to 13.4% of the time in men ≤65 years of age and 28.7% of the time in men >65 years of age.¹ In a recent study by Rosenhammer et al., HoLEP and TURP were match-paired to determine which procedure detected higher rates of incidental prostate cancer.² This study showed that 23.3% of HoLEP specimens detected incidental prostate cancer compared with 8.3% in TURP (p = 0.043).

The prostatic pathology analysis, in both of the cases in this report, was predominately composed of a cellular proliferation of spindle cells with rare scattered benign glands. Spindle cells in the prostate are seen in a wide variety of diagnoses and are not specific to any one disease. These entities are rare and are often difficult to distinguish. Immunohistochemical stains are typically required for definitive diagnosis.

In Case 1 of this report, the pathologic diagnosis was STUMP. STUMPs are frequently benign and represent a hyperplastic neoplastic process. STUMPs may involve either the transition zone or the peripheral zone, and may range in size from microscopic lesions to large cystic lesions up to 15 cm in size.³ The microscopic lesions are typically incidentally found.

STUMPs have an unpredictable course. Some STUMPs having coexisting stromal sarcoma at the time of biopsy and other STUMPs have been reported to appear on repeat biopsy, which suggests a malignant progression. A diagnosis of STUMP generally has a good prognosis as most cases are confined to the prostate and do not progress to sarcoma.

Case 2 is believed to be a sarcoma of the prostate with local invasion. Cystoprostatectomy was performed because of aggressive invasion of the bladder and pelvic sidewall. Case 2 is a rare case of adult spindled cell sarcoma with focal rhabdomyoblastic differentiation. This skeletal muscle malignancy is the most common lower urinary tract malignancy in the male pediatric population. Immunostaining showed myogenin negative, desmin positive, and focal myoD1 positive with osseous matrix formation. Desmin is an intermediate filament that is expressed in both smooth and skeletal muscle myocytes. It is also expressed in neoplasms with smooth or skeletal muscle differentiation. Desmin is positive in rhabdomyosarcoma, but a positive desmin is not enough to confirm skeletal muscle differentiation. Myogenin and/or MyoD1 are specific markers of skeletal muscle differentiation and should also be performed to confirm the diagnosis of rhabdomyosarcoma. Nuclear regulatory factor plays an important role in skeletal muscle differentiation. It is expressed by rhabdomyosarcomas.

Rhabdomyosarcoma is an exceedingly uncommon diagnosis in an adult with <20 cases ever reported in the literature.⁴ There are three subtypes of rhabdomyosarcoma: (1) embryonal, (2) alveolar, and (3) pleomorphic. The most common subtype is embryonal. In the pediatric population, embryonal rhabdomyosarcoma generally carries a good prognosis where as the adult population typically has a much worse prognosis with most patients dying <2 years after diagnosis, despite multimodal therapy.

Conclusion

HoLEP is a surgical treatment for BPH that results in enormous prostates. Infrequently, a large prostate will become significantly oversized because of rare underlying pathology analysis such as that presented in this case report. Low PSA values in young males with large prostate volumes are a common presenting scenario, although that was not the case in this report. Vigilance for the signs of rare underlying pathology analysis is recommended.

Abbreviations Used

BPH

benign prostatic hyperplasia

CT

computed tomography

HoLEP

holmium laser enucleation of the prostate

PR

progesterone receptors

PSA

prostate-specific antigen

STUMP

stromal tumor of uncertain malignant potential

TURP

transurethral resection of the prostate

Disclosure Statement

No competing financial interests exist.

Cite this article as: Brockway WJ, Navetta A, Soni P, El Tayeb MM (2019) Two cases of spindle cell neoplasms in patients undergoing holmium laser enucleation of the prostate, Journal of Endourology Case Reports 5:4, 174–177, DOI: 10.1089/cren.2019.0048.