Sebaceous induction in dermatofibroma: a common feature of dermatofibromas on the shoulder

An epidemiological study on skin tumors of the elderly in a community in Shanghai, China

The morbidity of skin tumors (ST) in China is a great concern as the population ages. No epidemiological survey on ST in elderly communities in China has been reported. A questionnaire survey was conducted among the residents over 60 years old in a community in Shanghai, China from May 1, 2011 to November 30, 2011. The prevalence of cutaneous tumors and associated factors were analyzed. Among 2038 valid cases, a total of 78 (3.8%, 95% CI 3.0-4.7) skin cancers (SC) were confirmed. According to the final multivariate regression analysis, age, gender and previous occupation were the significantly influential factors for SC. Actinic keratosis (AK) accounted for the largest proportion (63, 3.1%) in SC. The head and neck was the physiological site with the highest incidence of SC (64, 82.1%), and AK was the most common (55, 87.3%) in head and neck SC. The common concomitant diseases of SC were hypertension (26, 33.3%) and diabetes mellitus (9, 11.5%). Seborrheic keratosis (SK) was the most common benign skin tumor with a prevalence of 100%. Men and women developed SK in significantly different parts of the body (P < 0.0001). The incidence of ST in the elderly population in Shanghai community increased with age. ST preferred to occur in the head and neck, which might be attributed to excessive ultraviolet (UV) exposure in these areas. Therefore, early diagnosis and sun-protection education are essential interventions for ST in the elderly.

Challenging Patterns of Atypical Dermatofibromas and Promising Diagnostic Tools for Differential Diagnosis of Malignant Lesions

Dermatofibroma (DF) or fibrous histiocytoma is one of the most frequent benign cutaneous soft-tissue lesions, characterized by a post-inflammatory tissue reaction associated with fibrosis of the dermis. Clinically DFs have a polymorphous clinical aspect from the solitary, firm, single nodules to multiple papules with a relatively smooth surface. However, multiple atypical clinicopathological variants of DFs have been reported and, therefore, clinical recognition may become challenging, leading to a more burdensome identification and sometimes to misdiagnosis. Dermoscopy is considered an important tool in DFs diagnosis, as it improves diagnostic accuracy for clinically amelanotic nodules. Although typical dermoscopic patterns are most frequently seen in clinical practice, there have also been some atypical variants described, mimicking some underlying recurrent and sometimes harmful skin afflictions. Usually, no treatment is required, although an appropriate work-up may be necessary in specific cases, such as in the presence of atypical variants or a history of recent changes. This narrative review's aim is to summarize current evidence regarding clinical presentation, positive and differential diagnosis of atypical dermatofibromas and also to raise awareness about the importance of specific characteristics of atypical variants to better differentiate them from malignant conditions.

[Dermatofibroma with sebaceous induction]

BACKGROUND

Histiocytoma or dermatofibroma (DF) is a common benign skin tumour with several clinical and histopathological variants. Sebaceous induction overlying a dermatofibroma is rare and infrequently reported. Using a detailed clinical case, herein the semiological and dermoscopic features of this lesion are described and illustrated, and the differential diagnoses presented.

PATIENTS AND METHODS

A 52-year-old man consulted for a physical examination, which revealed a firm papular lesion of the upper middle back. The upper part of the nodule was covered by a slightly hyperpigmented surface, with numerous small whitish lobules. Microscopic examination revealed a dermatofibroma with sebaceous induction.

DISCUSSION

Sebaceous induction overlying a dermatofibroma is not frequent, and it occurs in most cases on or near the shoulder. The typical dermoscopic pattern involves many whitish globules or clumps grouped into clusters. The aetiology is unknown but could stem from a conducive microenvironment in shoulder skin, associated with growth factors secreted by the DF.

Induction of Desmoplastic Trichoepithelioma in a Dermatofibroma

Induction of follicular germinative structures above a dermatofibroma (DF) is a common finding. Rarely, induction of a trichoblastoma in a DF has been observed. Here, we report the case of a desmoplastic trichoepithelioma induced by a DF. The lesion with clinical and histological appearance of a DF situated on the left dorsal foot showed an associated adnexal proliferation that fulfilled histopathological criteria of desmoplastic trichoepithelioma. Immunohistochemistry (Ber-EP4, Bcl-2, CK17, CK20, CK7, EMA, and Ki67) helped to confirm the diagnosis and to exclude possible differential diagnoses.