Background: When physicians see an umbilical nodule, most of them instinctively recall the Sister Mary Joseph nodule. Therefore, dermatologists need to recognize umbilical dermatoses that can be mistaken for the Sister Mary Joseph nodules. This study aimed to describe the different kinds of benign umbilical tumors as well as elucidate the factors that can be used to distinguish the Sister Mary Joseph nodule from these tumors. Methods: The “benign umbilical tumor” group included 19 patients, whereas the “Sister Mary Joseph nodule” group comprised 30 patients (2 from our department, 28 from PubMed search). We compared the clinical and dermoscopic findings between 2 groups. Results: In the “benign umbilical tumor” group, the most common diagnosis was dermatofibroma (5/19), followed by keloid (3/19), and soft fibroma (3/19). These tumors had various colors (red, brown to black, and flesh colored) and exhibit characteristic surface changes (eg, verrucous changes in epidermal nevi and verrucae). Conversely, most Sister Mary Joseph nodules have an erythematous color, oozing or ulceration on the surface, and nearby satellite lesions. Furthermore, the dermoscopic findings of Sister Mary Joseph nodules showed a polymorphous vascular pattern and a white or milky-red, amorphous area. Benign lesions showed different dermoscopic patterns: pigment networks with white areas (dermatofibromas), thrombosed capillaries (verrucae), and the “pore sign” (epidermal cysts). Conclusions: Various cutaneous tumors can be mistaken for the Sister Mary Joseph nodule when they develop on the umbilicus; the clinical and dermoscopic differences found in this study may be useful for establishing a differential diagnosis.

Background Onychophagia is a common disorder affecting 20% to 30% of the general population. It is defined as habitual nail biting and can cause various changes in the nail units. However, to date, there has been a paucity of data focusing on nail deformities related to onychophagia. This study was performed to investigate the clinical characteristics of onychophagia in Korea.Methods This study included 53 patients with onychophagia who visited the Pusan National University Hospital (Busan and Yangsan) over a 10-year period (2011-2020). We retrospectively reviewed medical records and clinical and dermoscopic photographs.Results All 10 fingernails were affected in 37.7% of the patients. The left thumbnail was the most predominantly affected site (81.1%). Clinical findings showed that short nails with ragged distal borders were the most common presentation (100.0%), followed by generalized or patchy rough areas (50.9%), linear and pinpoint hemorrhage (32.1%), longitudinal melanonychia (30.2%), transverse groove (28.3%), brittleness (28.3%), macrolunula (24.5%), washboard nail (13.2%), and pterygium (3.8%). Of the patients, 88.7% had periungual complications, such as periungual exfoliation (77.4%), absent or ragged cuticle (52.8%), hyponychial hyperkeratosis (37.7%), and paronychia (15.1%).Conclusions Although onychophagia is a common disorder, its clinical characteristics have not been reported in the literature. The results of this study may be helpful in managing patients with onychophagia.December 2020 were included. All patients were at the outpatient clinic during their initial visits at Pusan National University Hospital (Busan and Yangsan) in Korea.

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