Figure 3 and 4: HIstopathological pictures of cutaneous leiomyoma
showing smooth muscles arranged in interlacing fascicles.
DISCUSSION
Cutaneous leiomyomas are rare benign, painful tumors arising from smooth
muscle fibres. According to site of origin, the types are pilar
leiomyoma, angioleiomyoma and dartoic leiomyoma, pilar leiomyoma being
the most common type. Pilar leiomyomas often occur as multiple and
disseminated or segmental pattern in 80% of the
cases.10 Multiple lesions are inherited as autosomal
dominant trait and may be associated with a condition termed Reed
syndrome. The predisposing gene for Reed syndrome is localized in
chromosome 1q42.3-43 which encodes Fumarate Hydratase (FH) gene. FH is
involved in Krebs cycle for conversion of fumarate to malate. Along with
this, FH is also believed to be a tumor suppressor gene and mutation of
FH leads to increased risk for developing renal
tumors.9,11 The lesions in multiple pilar leiomyomas
can be arranged in disseminated , blaschkoid or segmental(zosteriform )
patterns. Segmental pattern is further categorized into type 1 and type
2 segmental.
Histopathologically, pilar leiomyomas are circumscribed,
non-encapsulated tumors comprised of smooth muscles bundles arranged in
interlacing patterns, and sometimes in whorled pattern. The cells have
abundant eosinophilic cytoplasm and elongated nuclei with blunt ends.
Treatment of pilar leiomyomas remains frustrating. If the lesion is
solitary or few in number, excision can be considered. However, multiple
lesions are often treated symptomatically for pain. The treatment
options for pain in leiomyomas are calcium channel blockers like
nifedipine which blocks influx of calcium into smooth muscle, alpha
adrenergic blocking agents such as doxazocine and phenoxibenzamine, and
gabapentin and topical 9% hyoscine hydrobromide. CO2 laser, cryotherapy
and electrocoagulation are alternative treatments.7