- Email: [email protected]
Genital rhabdomyoma of the urethra in an infant girl
Human Pathology (2012) 43, 597–600
www.elsevier.com/locate/humpath
Case study
Genital rhabdomyoma of the urethra in an infant girl David Y. Lu MD a,⁎, Sue Chang MD a , Heather Cook MD b , Yalda Alizadeh MD, FRCPath c , Amer K. Karam MD b , Neda A. Moatamed MD a , Sarah M. Dry MD a a
Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA Department of Obstetrics and Gynecology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA c Department of Histopathology, St James's Hospital, Leeds Teaching Hospitals NHS Trust, Leeds LS9 7TF, UK b
Received 28 April 2011; revised 6 June 2011; accepted 7 June 2011
Keywords: Genital rhabdomyoma; Rhabdomyoblast; Striated muscle cell; Urethra
Summary Extracardiac rhabdomyomas are rare benign entities that usually occur in the head and neck region. Although genital rhabdomyoma is known to occur in the lower genital tract of young and middle-aged women, involvement of the anatomically adjacent urethra by rhabdomyoma is exceedingly rare. We present a case of genital rhabdomyoma arising from the urethra of an infant girl. The tumor was characterized by the submucosal presence of mature-appearing rhabdomyoblastic cells containing conspicuous cross-striations, with the cells set in a collagenous stroma. Necrosis and mitoses were absent. Skeletal muscle differentiation of the tumor cells was supported by positive immunohistochemical staining for desmin and myogenin. To our knowledge, this is the first case of urethral genitaltype rhabdomyoma in a child. © 2012 Elsevier Inc. All rights reserved.
1. Introduction Extracardiac rhabdomyomas are rare benign tumors of striated muscle that can be subdivided into adult, fetal, and genital types. Each of these types, which represent approximately 50%, 40%, and 10%, respectively, of extracardiac rhabdomyomas, has distinguishing clinicopathologic features [1]. Most extracardiac rhabdomyomas, particularly the adult and fetal types, occur in the head and neck region. Such lesions are very rare in the female genital tract, where they generally present in the vagina and vulva and rarely in the cervix. The genital tumors typically appear in women approximately 30 to 50 years of age (mean age, 42 years) and present as solitary, polypoid, submucosal, or subcutaneous masses that usually range in size from 1 to 3 cm [2]. Microscopically, most genital rhabdomyomas are ⁎ Corresponding author. E-mail address: [email protected] (D. Y. Lu). 0046-8177/$ – see front matter © 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.humpath.2011.06.012
covered by intact squamous epithelium and composed of benign, rather mature, round or strap-shaped rhabdomyoblasts separated by variable amounts of vascular fibromyxoid stroma. Due to their usual vaginal location, the main differential diagnoses are benign vaginal fibroepithelial polyp (FEP) and embryonal rhabdomyosarcoma, a malignant neoplasm. Urethral involvement by rhabdomyoma is exceptionally rare. We report what we believe is the first example of genital-type rhabdomyoma arising from the urethra in an infant girl.
2. Case report A 7-month-old girl was noted by her mother and pediatrician to have a growing mass protruding through the vaginal introitus. The mass was not associated with any apparent discomfort, discharge, bleeding, or evidence of
598 infection. The infant was otherwise healthy and was born as the result of a full-term uncomplicated vaginal delivery at 40 + 5/7 weeks gestation. Her mother's pregnancy was only complicated by gestational diabetes. There was no maternal toxic or teratogenic exposure. On examination of the infant in the clinic, a fleshy polypoid growth was noted in the region of the posterior vaginal introitus that was nontender to palpation. A punch biopsy was performed and sent to pathology. Ten days after the punch biopsy, the patient was taken to the operating room for an examination under anesthesia and excision of the mass. The patient was placed under general endotracheal anesthesia and positioned in dorsal lithotomy position. On examination, the polypoid mass was noted to be 1.5 cm in length with a 3-mm thin stalk that was actually attached to the distal posterior urethra. The base of the stalk was infiltrated with 1% lidocaine, and the entire lesion was excised with bovie cautery, and an indwelling Foley catheter was placed. The patient tolerated the procedure well, and the specimen was sent to pathology. Postoperatively, the patient did well, and the Foley was discontinued by her pediatrician on postoperative day 3. The patient returned to the clinic with her mother 2 weeks after surgery; her incision had healed completely. Four months after her original surgery, the patient was examined under anesthesia and underwent a cystoscopy and vaginoscopy, which did not reveal any evidence of disease recurrence.
D. Y. Lu et al. cells were round to oval, had smooth contours, and contained uniformly distributed chromatin with occasional prominent nucleoli. Necrosis and mitotic figures were not observed. The background stroma consisted of abundant collagenous tissue without prominent myxoid areas. Subsequent complete excision of the lesion showed, on gross examination, a polypoid, well-circumscribed mass measuring 2.0 × 1.5 × 0.9 cm. It was firm and covered by intact overlying smooth mucosa. The mucosa was white with focal erythematous areas, but no ulceration or mucosal disruption was grossly seen. Cut surface of the lesion was homogeneous and white with no hemorrhagic or necrotic areas noted. Histologic sections of the excision specimen demonstrated mucosa characterized by both nonkeratinized stratified squamous epithelium (Fig. 1) and urothelium (Fig. 2A), consistent with the lesion's location at the distal tip of the urethra adjacent to the vagina. The submucosa showed a less
3. Pathologic findings The punch biopsy of the mass from the posterior vaginal introitus region showed a submucosal lesion characterized by haphazardly arranged loose bundles of elongated to broad strap-shaped cells. These cells contained abundant eosinophilic cytoplasm with easily visible cross-striations, consistent with skeletal muscle differentiation. The nuclei of the
Fig. 1 Squamous mucosa with scattered striated muscle cells in the submucosa (objective, ×10; hematoxylin and eosin stain).
Fig. 2 Urethral orifice transitional mucosa with scattered striated muscle cells in the submucosa (A: objective, ×10; hematoxylin and eosin stain; B: objective, ×4; accompanying desmin immunohistochemical stain highlighting cytoplasm of striated cells).
Genital rhabdomyoma of the urethra in an infant girl
Fig. 3 Scattered striated muscle cells in submucosa at urethral orifice (objective, ×20; myogenin immunohistochemical stain highlighting nuclei of striated cells).
cellular but still conspicuous proliferation of relatively mature rhabdomyoblastic cells similar to those seen in the biopsy specimen. The tumor cells had centrally and peripherally located round bland nuclei with even chromatin and occasional prominent eosinophilic nucleoli. Crossstriations were noted, and mitotic figures and necrosis were still not seen. Immunohistochemical staining demonstrated that the tumor cells were positive for desmin (Fig. 2B) and myogenin (Fig. 3), markers that, together, confirmed skeletal muscle differentiation.
4. Discussion Rhabdomyomas are rare benign tumors that account for less than 2% of striated muscle tumors [3]. They are divided into cardiac and extracardiac types. Genital rhabdomyoma is a clinically and morphologically distinct subtype of extracardiac rhabdomyoma that almost always occurs in the vagina or vulva of young to middle-aged women. It is an uncommon tumor, with less than 30 cases reported in the vagina, 3 in the vulva, and 3 in the portio/cervix [4-6]. There has also been 1 reported case in the ovary [1] and 7 in the paratesticular region [7]. To our knowledge, before the current case, there have been no instances of genital-type rhabdomyoma arising from the urethra. Two cases of urethral rhabdomyoma occurring in boys have been mentioned in the Russian and French literature; however, they were deemed to be of a different subtype of extracardiac rhabdomyoma, specifically a fetal type [8,9]. Clinically, genital rhabdomyomas most often present as slow-growing, solitary, asymptomatic masses that are found incidentally; some other cases are accompanied by symp-
599 toms such as vaginal bleeding or dyspareunia. On gross examination, these rhabdomyomas are usually polypoid and firm and measure approximately 2 to 3 cm [5]. Ulceration and hemorrhage are not typical gross features. Microscopically, genital rhabdomyomas are covered by epithelium native to the site of the tumor; therefore, the epithelium is usually stratified squamous epithelium found on the vagina and vulva. The subepithelial stroma contains loosely arranged groups and/or interlacing fascicles of polygonal and strap-shaped cells with eosinophilic cytoplasm and easily observed cross-striations. Nuclei of the cells are generally bland, and mitoses are rare to absent. The cells are distributed in a background of variable amounts of collagen and mucoid material [3]. The rhabdomyoblastic nature of these cells has been confirmed by positive immunohistochemical staining for desmin, myoglobin, muscle-specific actin, and myosin [6] and by electron microscopic studies showing thin and thick myofilaments with I, A, and H bands and prominent Z lines [10]. The cells are negative for smooth muscle actin, cytokeratin, S-100, epithelial membrane antigen, and CD68. The differential diagnosis of genital rhabdomyoma occurring in the urethra includes other extracardiac rhabdomyomas, botryoid embryonal rhabdomyosarcoma (so-called sarcoma botryoides), and urethral FEP. Adult and fetal rhabdomyomas are the other 2 subtypes of extracardiac rhabdomyoma. Because they are characterized by some degree of skeletal muscle differentiation, they can be confused with genital-type rhabdomyomas. Adult rhabdomyomas are characterized by a mixture of large round to polygonal cells containing abundant eosinophilic cytoplasm and vacuolated polygonal cells. Cytoplasmic cross-striations are usually seen at least focally on hematoxylin-eosin staining. Fetal rhabdomyomas typically present in children but can also occur in adults. Their histologic presentation varies, ranging from tumors containing primitive ovoid to spindle-shaped cells admixed with immature skeletal muscle fibers in a myxoid background to those showing more mature skeletal muscle differentiation with little to no myxoid stroma [3]. Genital rhabdomyomas lack the vacuolated cells of adult rhabdomyomas, and they show more rhabdomyoblastic maturation and less variable cellular morphology than fetal rhabdomyomas [2]. Botryoid embryonal rhabdomyosarcoma is a rapidly growing malignant neoplasm that usually presents in children younger than 8 years. It is grossly observed as grape-like vesicles, often with ulceration of the overlying epithelium. Microscopically, a cambium layer—subepithelial condensation of primitive mesenchymal cells—separated from the overlying epithelium by a loose hypocellular zone is characteristically seen. Genital rhabdomyomas do not histologically exhibit a cambium layer. Furthermore, they demonstrate less nuclear pleomorphism and fewer mitotic figures than rhabdomyosarcomas [3]. Because the current case involved the distal urethra, a FEP of the urethra should also be in the differential
600 diagnosis. FEPs of the urethra are rare benign lesions that occur more commonly in children than in adults. They are extremely rare in girls. Unlike the tumor in the current case, FEPs of the urethra are characterized histologically by fibroconnective tissue containing vessels, smooth muscle fibers, and/or inflammatory infiltrates, without skeletal muscle-like fibers [11]. The pathogenesis of genital rhabdomyomas has not yet been well characterized. Some authors have postulated that these entities are hamartomas rather than true neoplasms, but if so, such lesions would be expected to occur in younger age groups than the adult groups in which they have been almost exclusively reported to be found [6]. In fact, there have only been 3 previously reported cases of possible genital rhabdomyomas occurring in or around the genital region of individuals younger than the teenage years—2 male infants with groin and scrotum rhabdomyomas [7] and an 8-year-old girl with rhabdomyoma of the labia [12]. Because genital rhabdomyomas are benign lesions, they are generally treated by local excision alone. There has only been 1 reported case of recurrence, present in the Italian literature [13]. No reports of metastases have been documented. Because of the rarity of genital rhabdomyomas, however, full characterization of such lesions is incomplete. As more examples are reported, the pathogenesis, clinical features, and prognosis of these tumors will be determined with more certainty. We hope by the presentation of this case to at least expand the clinical setting in which genital rhabdomyoma can occur to more young children and the urethra.
D. Y. Lu et al.
References [1] Huang T, Chen J, Ho WL. Ovarian serous cystadenoma with mural nodules of genital rhabdomyoma. HUM PATHOL 2005;36:433-5. [2] Kapadia SB, Barr FG. Rhabdomyoma. In: Fletcher CDM, Unni KK, Mertens F, editors. World Health Organization Classification of Tumours: Pathology & Genetics: Tumours of Soft Tissue and Bone. Lyon, France: IARCPress; 2002. p. 142-5. [3] Weiss SW, Goldblum JR. Rhabdomyoma. In: Weiss SW, Goldblum JR, editors. Enzinger and Weiss's Soft Tissue Tumors. 5th ed. Philadelphia (Pa): Mosby Elsevier; 2008. p. 583-94. [4] Lopez Varela C, Lopez de la Riva M, La Cruz Pelea C. Vaginal rhabdomyomas. Int J Gynaecol Obstet 1994;47:169-70. [5] Iversen UM. Two cases of benign vaginal rhabdomyoma: case reports. APMIS 1996;104:575-8. [6] Lin GY, Sun X, Badve S. Pathologic quiz case: vaginal wall mass in a 47-year-old woman. Arch Pathol Lab Med 2002;126:1241-2. [7] Davies B, Noh P, Smaldone MC, Ranganathan S, Docimo SG. Paratesticular rhabdomyoma in a young adult: case study and review of the literature. J Pediatr Surg 2007;42:E5-7. [8] Dodat H, Paulhac JB, Macabeo V, Bouvier R. Benign tumors of the posterior urethra in children. Apropos of an unusual case of rhabdomyoma of fetal type [in French]. J Urol (Paris) 1987;93:43-6. [9] Abdullaev FK, Nikolaev VV, Kulaev VD, Nazhimov VP. Endoscopic electroexcision of benign urethral tumors in children [in Russian] Urologiia 2009:63-6. [10] Gold JH, Bossen EH. Benign vaginal rhabdomyoma: a light and electron microscopic study. Cancer 1976;37:2283-94. [11] Demircan M, Ceran C, Karaman A, Uguralp S, Mizrak B. Urethral polyps in children: a review of the literature and report of two cases. Int J Urol 2006;13:841-3. [12] di Sant'Agnese PA, Knowles II DM. Extracardiac rhabdomyoma: a clinicopathologic study and review of the literature. Cancer 1980;46: 780-9. [13] Losi L, Choreutaki T, Nascetti D, Eusebi V. Recurrence in a case of rhabdomyoma of the vagina [in Italian]. Pathologica 1995;87:704-8.
www.elsevier.com/locate/humpath
Case study
Genital rhabdomyoma of the urethra in an infant girl David Y. Lu MD a,⁎, Sue Chang MD a , Heather Cook MD b , Yalda Alizadeh MD, FRCPath c , Amer K. Karam MD b , Neda A. Moatamed MD a , Sarah M. Dry MD a a
Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA Department of Obstetrics and Gynecology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA c Department of Histopathology, St James's Hospital, Leeds Teaching Hospitals NHS Trust, Leeds LS9 7TF, UK b
Received 28 April 2011; revised 6 June 2011; accepted 7 June 2011
Keywords: Genital rhabdomyoma; Rhabdomyoblast; Striated muscle cell; Urethra
Summary Extracardiac rhabdomyomas are rare benign entities that usually occur in the head and neck region. Although genital rhabdomyoma is known to occur in the lower genital tract of young and middle-aged women, involvement of the anatomically adjacent urethra by rhabdomyoma is exceedingly rare. We present a case of genital rhabdomyoma arising from the urethra of an infant girl. The tumor was characterized by the submucosal presence of mature-appearing rhabdomyoblastic cells containing conspicuous cross-striations, with the cells set in a collagenous stroma. Necrosis and mitoses were absent. Skeletal muscle differentiation of the tumor cells was supported by positive immunohistochemical staining for desmin and myogenin. To our knowledge, this is the first case of urethral genitaltype rhabdomyoma in a child. © 2012 Elsevier Inc. All rights reserved.
1. Introduction Extracardiac rhabdomyomas are rare benign tumors of striated muscle that can be subdivided into adult, fetal, and genital types. Each of these types, which represent approximately 50%, 40%, and 10%, respectively, of extracardiac rhabdomyomas, has distinguishing clinicopathologic features [1]. Most extracardiac rhabdomyomas, particularly the adult and fetal types, occur in the head and neck region. Such lesions are very rare in the female genital tract, where they generally present in the vagina and vulva and rarely in the cervix. The genital tumors typically appear in women approximately 30 to 50 years of age (mean age, 42 years) and present as solitary, polypoid, submucosal, or subcutaneous masses that usually range in size from 1 to 3 cm [2]. Microscopically, most genital rhabdomyomas are ⁎ Corresponding author. E-mail address: [email protected] (D. Y. Lu). 0046-8177/$ – see front matter © 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.humpath.2011.06.012
covered by intact squamous epithelium and composed of benign, rather mature, round or strap-shaped rhabdomyoblasts separated by variable amounts of vascular fibromyxoid stroma. Due to their usual vaginal location, the main differential diagnoses are benign vaginal fibroepithelial polyp (FEP) and embryonal rhabdomyosarcoma, a malignant neoplasm. Urethral involvement by rhabdomyoma is exceptionally rare. We report what we believe is the first example of genital-type rhabdomyoma arising from the urethra in an infant girl.
2. Case report A 7-month-old girl was noted by her mother and pediatrician to have a growing mass protruding through the vaginal introitus. The mass was not associated with any apparent discomfort, discharge, bleeding, or evidence of
598 infection. The infant was otherwise healthy and was born as the result of a full-term uncomplicated vaginal delivery at 40 + 5/7 weeks gestation. Her mother's pregnancy was only complicated by gestational diabetes. There was no maternal toxic or teratogenic exposure. On examination of the infant in the clinic, a fleshy polypoid growth was noted in the region of the posterior vaginal introitus that was nontender to palpation. A punch biopsy was performed and sent to pathology. Ten days after the punch biopsy, the patient was taken to the operating room for an examination under anesthesia and excision of the mass. The patient was placed under general endotracheal anesthesia and positioned in dorsal lithotomy position. On examination, the polypoid mass was noted to be 1.5 cm in length with a 3-mm thin stalk that was actually attached to the distal posterior urethra. The base of the stalk was infiltrated with 1% lidocaine, and the entire lesion was excised with bovie cautery, and an indwelling Foley catheter was placed. The patient tolerated the procedure well, and the specimen was sent to pathology. Postoperatively, the patient did well, and the Foley was discontinued by her pediatrician on postoperative day 3. The patient returned to the clinic with her mother 2 weeks after surgery; her incision had healed completely. Four months after her original surgery, the patient was examined under anesthesia and underwent a cystoscopy and vaginoscopy, which did not reveal any evidence of disease recurrence.
D. Y. Lu et al. cells were round to oval, had smooth contours, and contained uniformly distributed chromatin with occasional prominent nucleoli. Necrosis and mitotic figures were not observed. The background stroma consisted of abundant collagenous tissue without prominent myxoid areas. Subsequent complete excision of the lesion showed, on gross examination, a polypoid, well-circumscribed mass measuring 2.0 × 1.5 × 0.9 cm. It was firm and covered by intact overlying smooth mucosa. The mucosa was white with focal erythematous areas, but no ulceration or mucosal disruption was grossly seen. Cut surface of the lesion was homogeneous and white with no hemorrhagic or necrotic areas noted. Histologic sections of the excision specimen demonstrated mucosa characterized by both nonkeratinized stratified squamous epithelium (Fig. 1) and urothelium (Fig. 2A), consistent with the lesion's location at the distal tip of the urethra adjacent to the vagina. The submucosa showed a less
3. Pathologic findings The punch biopsy of the mass from the posterior vaginal introitus region showed a submucosal lesion characterized by haphazardly arranged loose bundles of elongated to broad strap-shaped cells. These cells contained abundant eosinophilic cytoplasm with easily visible cross-striations, consistent with skeletal muscle differentiation. The nuclei of the
Fig. 1 Squamous mucosa with scattered striated muscle cells in the submucosa (objective, ×10; hematoxylin and eosin stain).
Fig. 2 Urethral orifice transitional mucosa with scattered striated muscle cells in the submucosa (A: objective, ×10; hematoxylin and eosin stain; B: objective, ×4; accompanying desmin immunohistochemical stain highlighting cytoplasm of striated cells).
Genital rhabdomyoma of the urethra in an infant girl
Fig. 3 Scattered striated muscle cells in submucosa at urethral orifice (objective, ×20; myogenin immunohistochemical stain highlighting nuclei of striated cells).
cellular but still conspicuous proliferation of relatively mature rhabdomyoblastic cells similar to those seen in the biopsy specimen. The tumor cells had centrally and peripherally located round bland nuclei with even chromatin and occasional prominent eosinophilic nucleoli. Crossstriations were noted, and mitotic figures and necrosis were still not seen. Immunohistochemical staining demonstrated that the tumor cells were positive for desmin (Fig. 2B) and myogenin (Fig. 3), markers that, together, confirmed skeletal muscle differentiation.
4. Discussion Rhabdomyomas are rare benign tumors that account for less than 2% of striated muscle tumors [3]. They are divided into cardiac and extracardiac types. Genital rhabdomyoma is a clinically and morphologically distinct subtype of extracardiac rhabdomyoma that almost always occurs in the vagina or vulva of young to middle-aged women. It is an uncommon tumor, with less than 30 cases reported in the vagina, 3 in the vulva, and 3 in the portio/cervix [4-6]. There has also been 1 reported case in the ovary [1] and 7 in the paratesticular region [7]. To our knowledge, before the current case, there have been no instances of genital-type rhabdomyoma arising from the urethra. Two cases of urethral rhabdomyoma occurring in boys have been mentioned in the Russian and French literature; however, they were deemed to be of a different subtype of extracardiac rhabdomyoma, specifically a fetal type [8,9]. Clinically, genital rhabdomyomas most often present as slow-growing, solitary, asymptomatic masses that are found incidentally; some other cases are accompanied by symp-
599 toms such as vaginal bleeding or dyspareunia. On gross examination, these rhabdomyomas are usually polypoid and firm and measure approximately 2 to 3 cm [5]. Ulceration and hemorrhage are not typical gross features. Microscopically, genital rhabdomyomas are covered by epithelium native to the site of the tumor; therefore, the epithelium is usually stratified squamous epithelium found on the vagina and vulva. The subepithelial stroma contains loosely arranged groups and/or interlacing fascicles of polygonal and strap-shaped cells with eosinophilic cytoplasm and easily observed cross-striations. Nuclei of the cells are generally bland, and mitoses are rare to absent. The cells are distributed in a background of variable amounts of collagen and mucoid material [3]. The rhabdomyoblastic nature of these cells has been confirmed by positive immunohistochemical staining for desmin, myoglobin, muscle-specific actin, and myosin [6] and by electron microscopic studies showing thin and thick myofilaments with I, A, and H bands and prominent Z lines [10]. The cells are negative for smooth muscle actin, cytokeratin, S-100, epithelial membrane antigen, and CD68. The differential diagnosis of genital rhabdomyoma occurring in the urethra includes other extracardiac rhabdomyomas, botryoid embryonal rhabdomyosarcoma (so-called sarcoma botryoides), and urethral FEP. Adult and fetal rhabdomyomas are the other 2 subtypes of extracardiac rhabdomyoma. Because they are characterized by some degree of skeletal muscle differentiation, they can be confused with genital-type rhabdomyomas. Adult rhabdomyomas are characterized by a mixture of large round to polygonal cells containing abundant eosinophilic cytoplasm and vacuolated polygonal cells. Cytoplasmic cross-striations are usually seen at least focally on hematoxylin-eosin staining. Fetal rhabdomyomas typically present in children but can also occur in adults. Their histologic presentation varies, ranging from tumors containing primitive ovoid to spindle-shaped cells admixed with immature skeletal muscle fibers in a myxoid background to those showing more mature skeletal muscle differentiation with little to no myxoid stroma [3]. Genital rhabdomyomas lack the vacuolated cells of adult rhabdomyomas, and they show more rhabdomyoblastic maturation and less variable cellular morphology than fetal rhabdomyomas [2]. Botryoid embryonal rhabdomyosarcoma is a rapidly growing malignant neoplasm that usually presents in children younger than 8 years. It is grossly observed as grape-like vesicles, often with ulceration of the overlying epithelium. Microscopically, a cambium layer—subepithelial condensation of primitive mesenchymal cells—separated from the overlying epithelium by a loose hypocellular zone is characteristically seen. Genital rhabdomyomas do not histologically exhibit a cambium layer. Furthermore, they demonstrate less nuclear pleomorphism and fewer mitotic figures than rhabdomyosarcomas [3]. Because the current case involved the distal urethra, a FEP of the urethra should also be in the differential
600 diagnosis. FEPs of the urethra are rare benign lesions that occur more commonly in children than in adults. They are extremely rare in girls. Unlike the tumor in the current case, FEPs of the urethra are characterized histologically by fibroconnective tissue containing vessels, smooth muscle fibers, and/or inflammatory infiltrates, without skeletal muscle-like fibers [11]. The pathogenesis of genital rhabdomyomas has not yet been well characterized. Some authors have postulated that these entities are hamartomas rather than true neoplasms, but if so, such lesions would be expected to occur in younger age groups than the adult groups in which they have been almost exclusively reported to be found [6]. In fact, there have only been 3 previously reported cases of possible genital rhabdomyomas occurring in or around the genital region of individuals younger than the teenage years—2 male infants with groin and scrotum rhabdomyomas [7] and an 8-year-old girl with rhabdomyoma of the labia [12]. Because genital rhabdomyomas are benign lesions, they are generally treated by local excision alone. There has only been 1 reported case of recurrence, present in the Italian literature [13]. No reports of metastases have been documented. Because of the rarity of genital rhabdomyomas, however, full characterization of such lesions is incomplete. As more examples are reported, the pathogenesis, clinical features, and prognosis of these tumors will be determined with more certainty. We hope by the presentation of this case to at least expand the clinical setting in which genital rhabdomyoma can occur to more young children and the urethra.
D. Y. Lu et al.
References [1] Huang T, Chen J, Ho WL. Ovarian serous cystadenoma with mural nodules of genital rhabdomyoma. HUM PATHOL 2005;36:433-5. [2] Kapadia SB, Barr FG. Rhabdomyoma. In: Fletcher CDM, Unni KK, Mertens F, editors. World Health Organization Classification of Tumours: Pathology & Genetics: Tumours of Soft Tissue and Bone. Lyon, France: IARCPress; 2002. p. 142-5. [3] Weiss SW, Goldblum JR. Rhabdomyoma. In: Weiss SW, Goldblum JR, editors. Enzinger and Weiss's Soft Tissue Tumors. 5th ed. Philadelphia (Pa): Mosby Elsevier; 2008. p. 583-94. [4] Lopez Varela C, Lopez de la Riva M, La Cruz Pelea C. Vaginal rhabdomyomas. Int J Gynaecol Obstet 1994;47:169-70. [5] Iversen UM. Two cases of benign vaginal rhabdomyoma: case reports. APMIS 1996;104:575-8. [6] Lin GY, Sun X, Badve S. Pathologic quiz case: vaginal wall mass in a 47-year-old woman. Arch Pathol Lab Med 2002;126:1241-2. [7] Davies B, Noh P, Smaldone MC, Ranganathan S, Docimo SG. Paratesticular rhabdomyoma in a young adult: case study and review of the literature. J Pediatr Surg 2007;42:E5-7. [8] Dodat H, Paulhac JB, Macabeo V, Bouvier R. Benign tumors of the posterior urethra in children. Apropos of an unusual case of rhabdomyoma of fetal type [in French]. J Urol (Paris) 1987;93:43-6. [9] Abdullaev FK, Nikolaev VV, Kulaev VD, Nazhimov VP. Endoscopic electroexcision of benign urethral tumors in children [in Russian] Urologiia 2009:63-6. [10] Gold JH, Bossen EH. Benign vaginal rhabdomyoma: a light and electron microscopic study. Cancer 1976;37:2283-94. [11] Demircan M, Ceran C, Karaman A, Uguralp S, Mizrak B. Urethral polyps in children: a review of the literature and report of two cases. Int J Urol 2006;13:841-3. [12] di Sant'Agnese PA, Knowles II DM. Extracardiac rhabdomyoma: a clinicopathologic study and review of the literature. Cancer 1980;46: 780-9. [13] Losi L, Choreutaki T, Nascetti D, Eusebi V. Recurrence in a case of rhabdomyoma of the vagina [in Italian]. Pathologica 1995;87:704-8.