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ARTICLES |
Abstract
Leiomyomas of the genitourinary tract may originate from any structure containing smooth muscle. We report a case of scrotal leiomyoma in a 32 year old white male with a painless scrotal mass. Ultrasonography proved to be an accurate, rapid, and safe tool in the evaluation of the patientís scrotal mass. It is especially useful in differentiating intratesticular masses from those that are extratesticular. This is an important concept because intratesticular masses are frequently malignant and patients are treated with radical orchiectomy.
Leiomyomas of the genitourinary tract may originate from any structure containing smooth muscle.1,2,3,4 These benign tumors have been described in the kidneys, ureters, bladder, urethra, prostate, seminal vesicles, spermatic cord, testis, epididymis, penis, and scrotum. 3 The smooth muscle tumors of the scrotum were first described by Forster in 1858 and are reported to be an extremely rare.5 Siegal and Gaffey demonstrated the rarity of these tumors finding only 11 cases in a review of over 11,000 scrotal tumors.1 Smooth muscle tumors of non-visceral soft tissue can be divided into two categories: superficial subcutaneous lesions and deeper soft tissue lesions. Superficial tumors are further subdivided into: arrector pili in origin (pilar leiomyomas), blood vessels wall in origin (angioleiomyomas), and those arising in relation to smooth muscle found in the skin of the scrotum or vulva (genital leiomyomas).1
Case Report
A 32 year old white male was referred to our medical center complaining of a painless scrotal mass that had enlarged over a two year period. He had no constitutional symptoms and denied any history of scrotal trauma. The patient was previously treated with radioactive iodine for management of hyperthyroidism and remains euthyroid on thyroid hormone replacement. Physical examination was normal except for the presence of a solid mass in the mid-portion of the scrotum which was separate from the testicles or epididymides. Scrotal ultrasonography using a high frequency linear transducer demonstrated that the testicles and epididymides were normal. A solid midline mass with complex echotexture measuring 2.2 x 2.4 x 3.2 cm was demonstrated (Fig. 1). Blood flow to the mass was seen on duplex imaging.
The scrotal mass and surrounding skin were surgically resected using a vertical elliptical incision (Fig. 2). Interlacing and whorling smooth muscle were demonstrated on frozen section analysis (Fig. 3). Leiomyoma was the final histologic diagnosis. The predominant cell type was spindle with centrally located nuclei. Trichrome stains confirmed that there were muscle cells in the mass (Fig. 4). There was occasional nuclear pleomorphism, but no mitotic figures were detectable. Necrosis and vascular invasion were not detected. The patientís postoperative recovery was uneventful.
Comment
During the past 10 years, sonography has proved to be an accurate, rapid, and safe tool in the evaluation of scrotal masses6. It is especially useful in differentiating intratesticular masses from those that are extratesticular.6 This is an important concept because intratesticular masses are frequently malignant and patients are treated with radical orchiectomy. Benign lesions can be simply excised. Scrotal ultrasonography approaches near 100% accuracy rate in distinguishing intratesticular lesions from extratesticular lesions.7,8
Over the years, the typical gray scale image has been enhanced by the addition of color-assigned blood flow information and spectral waveform analysis. For real time gray scale sonography, a short focused high resolution 7.5-10 MHz transducer is used. Standard longitudinal and transverse views of each testis and epididymis are obtained. A transverse view with both testes on the same image permits direct comparison of subtle echotexture changes. The normal testis demonstrates homogeneous echotexture of low-medium echogenicity. It is an ovoid-shape gland measuring 3-5 cm in length and 2-3 cm in width9.
An intratesticular lesion is malignant until proven otherwise7,9. An
extratesticular lesion is more likely the result of inflammation, trauma, or benign
neoplasm9. Hydrocele is the most common extratesticular mass and typically
anechoic on ultrasonography7. The most common extratesticular scrotal
neoplasm is the adenomatoid tumor of the epididymis, a benign lesion accounting for
30% of extratesticular tumors and appears hyperechoic10.
Because of their extreme rarity, scrotal leiomyomas are often confused with fibroma
or an epidermal inclusion cyst and are nearly always misdiagnosed preoperatively.
5 Scrotal leiomyoma appear most often in white men between the fourth
and sixth decade.1,11 They are typically painless, non-inflamed, small
cutaneous lesions usually present on average of 7.6 years between patient recognition
and surgical removal.1,5 They tend to be solitary, asymptomatic lesions
measuring 1-14 cm with a mean length of 6.4 cm.1 All reported scrotal
leiomyomas have been composed of spindle cells, having a cigar-shaped nuclei with
eosinophilic cytoplasm frequently containing desmin,1,2,12 Massonís trichrome,
which stains collagen green and muscle red is utilized to confirm the diagnosis of
leiomyoma.2 The differential diagnosis of scrotal lesions distinctly separate
from the testis and adnexal structures includes squamous cell carcinoma, basal cell
carcinoma, Pagetís disease, fibroma, lipoma, myxoma, hemangioma, lymphangioma, liposarcoma,
rhabdomyosarcaroma, leiomyosarcoma, epidermal inclusion cyst , and leiomyoma.5
Although rare, this lesion should be considered in the differential diagnosis
of a scrotal mass. If there is any doubt regarding the extent for surgical excision
of scrotal masses not associated with the testicle or epididymis, ultrasonography
and pathologic frozen sections should be utilized to confirm the clinical suspicion
of a benign versus malignant scrotal lesion.
References
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