Cutaneous leiomyoma: novel histologic findings for classification and diagnosis.

Smooth muscle tumors rather benign or malignant can arise wherever the muscular tissue presents but cutaneous leiomyoma is one of the rare benign tumors of the which even the diagnostic criteria from the malignant type of the tumor is still in doubt. This study was aimed to compare the subtypes of cutaneous leiomyoma from different histologic aspects in order to find unique criteria for better classification and diagnosis. The six year data base of our center was reviewed and 25 patients with cutaneous leiomyoma were included in this study. Of 25 patients, 5 were female and 20 were male. 5 patients had angioleiomyoma (ALM) and 20 had pilar leiomyoma (PLM). ALM had following characteristics: dilated vascular canals intermingled with compact smooth muscle bundles; well circumscribe counter and myxoid and hyaline changes through the tumor. In contrast, PLMs had following histologic features: poor defined outline, entrapped hair follicles and eccrine glands, acanthosis and elongated rete ridges with hyperpigmentation and smooth muscle bundles which are interdigitated with elongated rete ridges. Here we introduced some distinct histological features for each subtype of the cutaneous leiomyoma which can lead to create novel criteria for classification and diagnosis of the lesion.