Unusual presentation of cutaneous leiomyoma.

Herein, we report a case of leiomyoma cutis because of its rarity and unusual presentation. The case presented with a solitary leiomyoma lesion which was painless. However, the adjacent normal appearing area was tender. A biopsy of the lesion as well as of a portion of the adjacent normal appearing area was taken, which confirmed the diagnosis of cutaneous leiomyoma. This may suggest the dormant nature of the disease which has not yet become apparent.

What was known?

Leiomyomas are painful smooth muscle tumors.

Introduction

Leiomyomas are benign painful soft-tissue neoplasms that stem from the erector pili muscle, the muscular layer of blood vessels, and the tunica dartos, labia majora, or nipple. There are three types: (a) Piloleiomyoma (cutaneous leiomyomas, leiomyoma cutis); (b) dartoic leiomyoma; and (c) angioleiomyoma.[1] Cutaneous leiomyomas comprise about 5% of all leiomyomas.[2] This report is to highlight an unusual presentation of leiomyoma cutis.

Case Report

A 55-year-old male patient presented with a 4 year history of solitary painless swelling over the anterior abdominal wall. To start with the lesion was small in size, which gradually increased to attain the present size of about 5 mm. A year later he noticed pain adjacent to the nodule which aggravated on pressure. There was no family history.

Cutaneous examination revealed a single firm skin colored nodule over the abdomen just above the umbilical area [Figure 1]. On palpation, the nodule was non-tender, however, the area adjacent to the lesion was tender. Histopathology of the lesion as well as of a portion of the adjacent normal appearing skin was done, which showed short fascicles and whorls of spindled smooth muscle cells in the dermis which confirmed the diagnosis of cutaneous leiomyoma. The diagnosis was further confirmed by using Masson's Trichome stain (MTS) which stained the smooth muscles pink [Figure 2].

Figure 1

Single skin colored nodule over the anterior abdominal wall

Figure 2

Dermis depicts a circumscribed spindle cell tumor with cells oriented in short fascicles. The spindle cells are stained pink and the adjacent collagen blue (MTS), original magnification × 10

Discussion

Leiomyoma cutis are relatively uncommon benign tumors of smooth muscle derived from the arrector pili muscle. They may present as solitary as well as multiple lesions.[3] Most leiomyomas are sporadic, but it has been suggested that multiple leiomyomas may be inherited as an autosomal dominant trait.[4] Patients with piloleiomyomas often have pain that may be spontaneous or secondary to cold, pressure, or emotion.[5] The pathogenesis of pain associated with these lesions is unresolved. Some reports suggest that pain could result from local pressure by tumor on cutaneous nerves, whereas others have hypothesized that muscle contraction may be central to induction of pain.[6]

Interesting fact in our case was the patient presented with a solitary leiomyoma lesion which was painless. However, the adjacent normal looking skin was tender. Though the leiomyoma lesion may at times be painless, the reason as to why the adjacent area was tender is not understood, probably suggesting the dormant nature of the disease which has not yet become apparent and may progress to develop into a classical leiomyoma lesion later on. Further studies may be required to substantiate our conclusion.

What is new?

Painless leiomyoma tumor with adjacent tender area probably showing the dormant nature of the disease.