Digital myxoid cysts: 12-year experience from two Italian Dermatology Units

Digital mucous cysts (DMCs) are benign, translucent, fluid-filled asymptomatic, slow-growing, dome-shaped nodules overlying a joint or tendon sheath on the distal dorsal side of the fingers or, more rarely, on the toes. They are degenerative in nature and are often associated with interphalangeal joint arthritis. Although DMCs are usually solitary, multiple cysts have been observed to develop simultaneously. They can sometimes be painful, confer a reduction in motility, and cause weakness and deformity in the nails. Spontaneous regression is rare, and intervention using surgical or non-surgical treatment is advisable.

We analyzed 53 DMCs of 51 patients treated in two Italian Dermatology Units between January 2004 and March 2015. The aim of this study was to evaluate the most salient clinical, histopathological and dermoscopic features, in addition to the response to treatment. We then compared the data to assess whether the histological type (ganglion-type or focal dermal mucinosis-type) or immunohistochemical phenotype of DMCs is correlated with the likelihood of relapse. All the patients have been treated with simple surgical excision with a cure rate of 72.6% at a mean recurrence time of 160 days with a mean follow-up of 3.6 years.

Histopathological examination, performed in 11 out of the 53 cysts, revealed 7 cases of ganglion-type cysts and 4 cases of focal cutaneous mucinosis-type cysts. No correlation was detected between histopathological type and recurrence.

Digital dermoscopy confirmed the pattern recently reported in the literature, providing confidence in the clinical diagnosis and reducing the need for preoperative radiography or ultrasound imaging.