Sebaceous induction in dermatofibroma: a common feature of dermatofibromas on the shoulder.
BACKGROUND
Dermatofibroma (DF) has multiple histopathological variants and overlying acanthosis, hyperkeratosis and hyperpigmentation are often present. We have frequently observed sebaceous induction in DFs on the shoulder and wanted to assess if this is a site-specific finding.


METHODS
We prospectively collected 100 DFs and assessed for sebaceous induction, the histopathologic pattern of the DF and any associated-epidermal changes. We retrospectively searched for DFs with sebaceous induction to assess the anatomic site of the biopsy.


RESULTS
In the 100 prospectively collected DFs, 49% occurred on the lower extremities, 39% on the upper extremities, 10% on the trunk and 2% on the head. Sebaceous induction was present in 16 DFs, 81% of which occurred on or near the shoulder. The most common variant was fibrocollagenous DF (64%), including in DFs with sebaceous induction. The retrospective search for DFs with sebaceous induction found 19 cases in which 95% occurred on the shoulder area. Sclerotic pattern DFs were most common in this retrospective cohort (47%), and seborrheic keratosis-like hyperplasia occurred in 100% of these cases.


CONCLUSIONS
DFs occurring on the shoulder have a high incidence of sebaceous induction with seborrheic keratosis-like epidermal hyperplasia and a fibrocollagenous or sclerotic pattern.
Department of Pathology and Dermatology, University of California, San Francisco, CA, USA.
Majid
M
Zeidi
Department of Pathology and Dermatology, University of California, San Francisco, CA, USA.
Jeffrey P
JP
North
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D002648:Child; D003937:Diagnosis, Differential; D005260:Female; D018219:Histiocytoma, Benign Fibrous / Q000473:pathology*; D006801:Humans; D017492:Keratosis, Seborrheic / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012189:Retrospective Studies; D012598:Sclerosis / Q000473:pathology; D012626:Sebaceous Gland Neoplasms / Q000473:pathology*; D012782:Shoulder / Q000473:pathology*; D012878:Skin Neoplasms / Q000473:pathology*; D055815:Young Adult
dermatofibroma (DF); follicular; induction; sebaceous; shoulder