CLINICAL PATHOLOGY CASE Genital Desmoplastic Fibroblastoma (Collagenous Fibroma) Department of Urology, Pathol- ogy, Plastic Surgery Daegu Cath- olic University Medical Center, Daegu, Republic of Korea. Corresponding Author: Jae shin Park, MD Department of Urology, Daegu Catholic University Medical Cen- ter, Daegu, Republic of Korea. Tel: +82 53 6504662 E-mail: jspark@cu.ac.kr Received January 2014 Accepted June 2014 Jae Shin Park, Kwon Ho Bae, Hoon Kyu Oh, Jae Bok Park, Dae Hwan Park Keywords: scrotum; genital neoplasms, male; diagnosis; fibroma; desmoplastic. INTRODUCTION Desmoplastic fibroblastomas (DFs) are rare fibrous soft tissue tumors that usually arise in subcuta-neous tissue or skeletal muscle in a variety of anatomical sites. This was first described by Evans in 1995 and was classified as a distinctive form of benign fibrous soft tumor.(1) In 1996 the lesion was renamed as a “ collagenous fibroma” by Nielsen and colleagues.(2) The arm or the shoulders are the most frequent sites of involvement. They have also been described in the neck, tongue, lacrimal gland and palate.(3-7) To the best of our knowledge, we report the first case of DF (collagenous fibroma) occurring in genital area. CASE REPORT A 71-year old man presented with a giant multiple globular mass in the scrotum which has grown slowly for Figure 1. The 20 × 15 cm sized, homogeneous pearl-grey colored, firm globular mass in the scrotum has extended to adjacent penis and left inner thigh. Penile glans was not appreciable. Figure 2. Computed tomography scan showed a 15 × 9 cm sized soft tissue mass in the scrotum (yellow arrow) and penis which has extended into the fas- cial area of left inner thigh (white arrows). Penile glans (red arrow) is trapped in within the mass. 1849 Clinical Pathology Case UROLOGY JOURNAL Vol. 11 No. 04 July - August 2014 1850 Genital Desmoplastic Fibroblastoma-Park et al DISCUSSION DFs also known as collagenous fibromas are benign soft tissue paucic- ellular tumors. They are usually well circumscribed and are composed of spindle to stellate shaped fibroblasts dispersed in a fibromyxoid or densely fibrous background stroma with low mitotic activity. So, Mi- ettinen and Fetsch recommended the designation stellate cell fibroma. Immunohistochemical and ultrastructural studies show that the tumor cells are predominantly fibroblastic in nature and typically positive for vimentin.(3) There is often focal reactivity for muscle actins (HHF-35) and α-smooth muscle actin.(3) Scattered CD68-positive histiocytes and mast cells may be present, but the tumor cells are negative. There is no documented immunoreactivity for CD34, S-100 protein, desmin, or epithelial membrane antigen (EMA). The lesion typically presents with a long history of a painless, slowly growing well-circumscribed subcutaneous mass occurring predominantly in males, with a median age of 50 years.(1,2) Since 1995, approximately 94 cases of DF have been reported in the literature with the largest case series of 63 pa- tients being published by Miettinen and Fetsch.(3) It appears in a vari- ety of peripheral sites with the most common location being the arm, shoulder, lower limb, back, forearm, hands, feet, neck and even in the tongue, lacrimal gland , palate and parotid gland.(3-8) CONCLUSION In conclusion, the present case is the first description of a DF that has involved the genital area. The clinical, gross and histologic features are those of a benign neoplasm. We highlight this peculiar lesion and wish to increase awareness of these rare lesions among urologists and pathologists alike. CONFLICT OF INTEREST None declared. REFERENCES 1. Evans HL. Desmoplastic fibroblastoma. A report of seven cases. Am J Surg Pathol. 1995;19:1077-81. 2. Nielson GP, O’Connel JX, Dickersin GR, Rosenberg AE. Collagenous fibroma (desmoplastic fibroblastoma): A report of seven cases. Mod Pathol. 1996;9:781-5. 3. Miettinen M, Fetsch JF. Collagenous fibroma (desmoplastic fibroblasto- ma): A clinicopathologic study of 63 cases of a distinctive soft tissue - lesion with stellate-shaped fibroblasts. Hum Pathol. 1998;29:676-82. 4. Watanabe H, Ishida Y, Nagashima K, Makino T, Norisugi O, Shimizu T. Desmoplastic fibroblastoma (collagenous fibroma). J Dermatol. 2008;35:93-7. 5. Nonaka CF, de Carvalho MV, de Moraes M, de Medeiros AM, de Fre- itas AR. Desmoplastic fibroblastoma (collagenous fibroma) of the tongue. J Cutan Pathol. 2010;37:911-4. 6. Ahn M, Osipov V, Harris GJ. Collagenous fibroma (desmoplastic 4 years. On physical examination, a giant multiple globular mass in the scrotum has extended to adjacent penis and left inner thigh. Penile glans was not appreciable (Figure 1). He had no history of genital sur- gery. A pelvic computed tomography (CT) scan showed a soft tissue mass in the scrotum and penis which has extended into the fascial area of left inner thigh (Figure 2). The patient underwent total excision of the mass in the scrotum, penis and left inner thigh. Skin defect in pe- nile shaft and scrotum were managed with penile skin graft and scroto- plasty (Figure 3). On pathology, the resected penile and scrotal mass- es measures 17.5 × 11 cm and 12 × 8 cm, respectively, with vaguely circumscribed subcutaneous lesion with convoluted skin surface. The cut surface was whitish grey in color without hemorrhage or necrosis. Microscopically, the mass was paucicellular and consists of widely spaced bland spindle- to stellate-shaped fibroblasts embedded in a collagenous and myxocollagenous stroma (Figure 4). Cellular atyp- ia or abnormal mitosis was absent. The immunohistochemical stains showed vimentin positive in stellated fibroblast, but, desmin, smooth muscle actin, S-100 protein, CD34, CD68, factor-8, myoglobin and neurofilament were negative. Tumor recurrence was not observed for 12 months. Figure 3. Postoperative finding after excision of mass. Penile glans is exposed. Figure 4. Microscopically, the tumor has been composed of hypocellular spindle to stellate shaped fibroblasts and myofibroblasts embedded in a prominent collagenous stroma (white arrows) (Hematoxylin and eosin stains × 100). fibroblastoma) of the lacrimal gland. Ophthalmic Plast Reconstr Surg. 2009;25:250-2. 7. Mesquita RA, Okuda E, Jorge WA, de Arau´jo VC. Collagenous fibroma (desmoplastic fibroblastoma) of the palate: a case report. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2001;91:80-4. 8. Vinayak Nagaraja, Hedley G. Coleman,Gary J. Morgan. Desmoplastic Fibroblastoma Presenting as a Parotid Tumour: A Case Report and Re- view of the Literature. Head Neck Pathol. 2013;7:285-90. 1851 Clinical Pathology Case