Ann Dermatol Vol. 23, No. 2, 2011 DOI: 10.5021/ad.2011.23.2.185 ORIGINAL ARTICLE A Clinical and Histopathological Study of 122 Cases of Dermatofibroma (Benign Fibrous Histiocytoma) Tae Young Han, M.D., Hee Sun Chang, M.D., June Hyun Kyung Lee, M.D., Won-Mi Lee, M.D.1, Sook-Ja Son, M.D. Departments of Dermatology and 1Pathology, Eulji General Hospital, College of Medicine, Eulji University, Seoul, Korea Background: Many variants of dermatofibromas have been INTRODUCTION described, and being aware of the variants of derma- tofibromas is important to avoid misdiagnosis. Objective: Dermatofibroma (benign fibrous histiocytoma) is a We wanted to evaluate the clinical and pathologic common skin lesion and it accounts for approximately 3% characteristics of 122 cases of dermatofibromas. Methods: of the skin lesion specimens received by one derma- We retrospectively reviewed the medical records and 122 topathology laboratory1. There is a predilection for derma- biopsy specimens of 92 patients who were diagnosed with tofibroma to develop on the extremities, and particularly dermatofibroma in the Department of Dermatology at Eulji on the lower extremities of young adults. There is a female Hospital of Eulji University between January 2000 and preponderance amongst the patients with dermatofib- March 2010. Results: Nearly 80% of the cases occurred roma1. Dermatofibroma is round or ovoid, firm, dermal between the ages of 20 and 49 years, with an overall nodules and they are usually ＜1 cm in diameter2. The predominance of females. Over 70% of the lesions were diagnosis is usually straightforward if the classical clinical found on the extremities. The most common histologic and pathologic features are evident. However, many variant was a fibrocollagenous dermatofibroma (40.1%). variants of dermatofibromas have been described, and Other variants included histiocytic (13.1%), cellular knowledge of these variations is important to avoid a (11.5%), aneurysmal (7.4%), angiomatous (6.5%), sclerotic misdiagnosis of a possibly more aggressive tumor. The (6.5%), monster (4.9%), palisading (1.6%) and keloidal main histologic variants include fibrocollagenous, cell- dermatofibromas (0.8%). There were 9 dermatofibromas ular3, histiocytic4, lipidized5, angiomatous6, aneurysmal7, (7.3%) that were the mixed type with two co-dominant clear cell8, monster cell9, myxoid10, keloidal11, palisad- histologic features. Conclusion: The results of this study are ing12, osteoclastic13 and epithelioid dermatofibroma14. consistent with previous reports on the clinical features of There are no prior Korean reports regarding the detailed dermatofibromas. However, we observed several characteri- classification of the histologic features of dermatofib- stic subtypes of dermatofibroma and we compared the romas. Therefore, we report here on a series of 122 cases frequency of the histologic subtypes. (Ann Dermatol 23(2) of dermatofibroma and we discuss the clinical and 185∼192, 2011) histopathologic features. -Keywords- MATERIALS AND METHODS Dermatofibroma We performed a retrospective review of the medical records and 122 biopsy specimens of 92 patients who were diagnosed with dermatofibroma in the Department Received October 11, 2010, Revised January 4, 2011, Accepted for of Dermatology at Eulji Hospital of Eulji University publication January 4, 2011 between January 2000 and March 2010. Corresponding author: Sook-Ja Son, M.D., Department of Dermatology, Eulji General Hospital, College of Medicine, Eulji University, 280-1 Clinical features Hagye 1-dong, Nowon-gu, Seoul 139-711, Korea. Tel: 82-2-970-8280, Fax: 82-2-974-1577, E-mail: ssjmdderma@ eulji.ac.kr The following clinical data was collected: age, gender, Vol. 23, No. 2, 2011 185 TY Han, et al duration, size, number, the distribution of the lesions, patient was 8 years of age and the oldest patient was 72 symptoms, color, a history of trauma, the clinical years of age, and the mean age was 36.2 years. Greater configuration and the clinical diagnosis of the lesions. than 80% of the tumors were diagnosed in patients between 20 and 49 years of age. The highest frequency of Histopathologic features tumor according to age was between 20 and 29 years of All of the cutaneous samples were fixed in formalin, age (31.5%; Fig. 1). processed and embedded in paraffin. The sections were 2) Duration, size, color, number and clinical configura- stained with hematoxylin and eosin. The samples were tion of the lesions classified as variants of dermatofibromas (fibrocollagen- The number of tumors that persisted for ＜2 years was 71 ous, sclerotic, cellular, histiocytic, aneurysmal, angioma- (58.2%) and 51 tumors (41.8%) persisted for ＞2 years. tous, keloidal, monster, palisading and mixed) according The size of the tumor on examination varied from 0.3∼5 to the dominant pathologic features. When the cellular cm, with most of the tumors ＜2 cm in size (n=117, type of dermatofibroma was suspected, immunohisto- 85.2%; Fig. 2). The tumors appeared as various colored chemical staining (CD34 and factor XIIIa) was performed lesions. The most common color was brown (n=51, to differentiate it from a dermatofibrosarcoma protuberans 41.8%). The second most common color was pink-red (DFSP). In addition, the depth of invasion, the epidermal (n=40, 32.8%), followed by skin color (n=28, 23.0%). changes (hyperkeratosis, acanthosis and basal layer hyper- Three cases (2.45%) were blue in color. The majority of pigmentation), the presence of a grenz zone, formation of the patients had a single lesion (n=74, 80.4%; Fig. 3). lymphoid nodules and mucin deposition were determin- Based on the clinical configuration of the lesion, the ed. tumors were divided into the following four groups: flat, Statistical analysis Statistical analysis was performed using the χ2 test and Fisher’s exact test, where appropriate. p-values ≤0.05 were considered statistically significant. All the data was analyzed using SPSS 12.0 (SPSS Inc., Chicago, IL, USA). RESULTS Clinical findings 1) The age and gender ratio Among the 92 studied patients, dermatofibroma was more common in females than in males (26 and 68, respec- tively; the male-to-female ratio was 1:2.6). The youngest Fig. 2. The size of the lesions. Fig. 1. The age and gender distribution of the patients. Fig. 3. The number of lesions per each patient. 186 Ann Dermatol A Clinical & Histopathological Study of of DF dome-shaped, polypoid and depressed. The most comm- tumors were asymptomatic (n=71, 58.2%). Twenty-five on configuration was dome-shaped (n=84, 68.9%; Fig. 4). (20.5%) tumors were tender, 14 were painful (11.5%) and 3) Distribution of the lesions 12 tumors were pruritic (58.2%). The most common location of tumors was the legs (n=52, 5) Clinical diagnosis of the lesions 42.6%), followed by the arms (n=37, 30.3%). Table 1 The correct pre-operative diagnosis was made in 100 lists the distribution of the dermatofibromas. The arms, cases (82.2%). The most common clinical impression was legs, buttocks, chest, face, abdomen, back, hand, and feet a dermatofibroma with a wide range of other possible were affected in decreasing frequency. No dermatofib- diagnosis, including an epidermal cyst (8.7%), pilomatri- roma was observed on the scalp or neck (Fig. 5). coma (3.5%), eccrine poroma (2.9%), dermatofibrosar- 4) History of trauma and symptoms coma protuberans (2.9%), intradermal nevus (2.9%), Three tumors occurred at the site of an insect bite, and leiomyoma (2.9%), keloid (2.9%), soft fibroma (1.5%) and one case occurred at the site of a piercing. Most of the trichilemmal cyst (1.5%). Fig. 4. Configuration of the lesions. Fig. 5. Distribution of the lesions (%). Table 1. Summary of the histopathological features Invasion depth Epidermis change Superficial Deep p- Basal Type Dermis Hyperkeratosis Acanthosis GZ LN Mucin subcutis subcutis value pigmentation (%) (%) (%) (%) (%) (%) Fibrocollagenous 26 (53.0) 20 (40.8) 3 (6.1) NS 33 (67.3) 35 (71.4) 40 (81.6) 37 (71.4) 8 (16.3)* 8 (16.3) Histiocytic 9 (56.3) 7 (43.8) 0 (0) NS 13 (81.3) 12 (75.0) 11 (68.8) 10 (75.0) 0 (0) 1 (6.3) Cellular 7 (50.0) 7 (50.0) 0 (0) NS 11 (78.6) 11 (78.6) 6 (42.9)† 10 (78.6) 1 (7.1) 4 (28.6) Aneurysmal 2 (22.2) 6 (66.7) 1 (11.1) ＜0.05† 6 (66.7) 3 (33.3)† 4 (44.4) 3 (33.3) 1 (11.1) 0 (0) Sclerotic 7 (87.5) 1 (12.5) 0 (0) NS 3 (37.5) 7 (87.5) 6 (75.0) 7 (87.5) 1 (12.5) 2 (25.0) Angiomatous 7 (87.5) 1 (12.5) 0 (0) NS 5 (62.5) 6 (75.0) 7 (87.5) 7 (87.5) 0 (0) 2 (25.0) Monster 2 (33.3) 4 (66.7) 0 (0) NS 4 (66.7) 6 (100) 4 (66.7) 6 (100) 0 (0) 0 (0) Palisading 2 (100) 0 (0) 0 (0) NS 0 (0) 2 (100) 0 (0) 1 (50.0) 1 (50.0) 0 (0) Keloidal 1 (100) 0 (0) 0 (0) NS 1 (100) 1 (100) 1 (100) 1 (100) 0 (0) 0 (0) Fibrocollagenous＋ 3 (60.0) 2 (40.0) 0 (0) NS 3 (60.0) 5 (100) 5 (100) 2 (40.0) 0 (0) 0 (0) Histiocytic Sclerotic＋ 2 (100) 0 (0) 0 (0) NS 2 (100) 2 (100) 2 (100) 2 (100) 0 (0) 0 (0) Fibrocollagenous Fibrocollagenous＋ 1 (100) 0 (0) 0 (0) NS 0 (0) 1 (100) 1 (100) 1 (100) 0 (0) 0 (0) Angiomatous Cellular＋Histiocytic 1 (100) 0 (0) 0 (0) NS 1 (100) 1 (100) 1 (100) 0 (0) 0 (0) 0 (0) Total 70 (57.4) 48 (39.3) 4 (3.3) NS 82 (67.2) 92 (75.4) 88 (72.1) 87 (71.3) 12 (9.8) 17 (13.9) *Evaluated by the χ2 test, with the significance set at ＜0.05.