๐ ็ธฝ็ฎ้ ๏ฝ ๐ ่ฑๆๅๆ๏ผๆฌ็ฏ๏ผ ๏ฝ ๐ ๅฎๆด็ฟป่ญฏ ๏ฝ โญ ็ฒพ่ฏ็ญ่จ
Rhabdomyomatous mesenchymal hamartoma
Rhabdomyomatous mesenchymal hamartoma
Clinical features Rhabdomyomatous mesenchymal hamartoma (also known as striated muscle hamartoma) is a very rare congenital lesion.1โ8 It presents in neonates and infants as one or more polypoid lesions simulating skin tags in the head and neck region (including intraoral lesions), especially on the central face.9โ14 Exceptional cases have been described in the perianal area, sacral area vagina, sternoclavicular area and on a digit.15โ19 Unusual clinical presentations include subcutaneous lesions, a case resembling morphea โen coup de sabre,โ one mimicking a basal cell carcinoma and another presenting as a plaque.20โ25 Multiple lesions are exceptional and a bilobulated case has been described.26,27 Occasional cases have been associated with other congenital abnormalities including cleft lip, preauricular sinuses, sclerocorneas, low-set ears, thyroglossal sinus, colobomata, dermoid cysts, microphthalmia, spinal dysraphism, and meningocele.7,8,28โ30 It appears that some of the lesions seen in Delleman syndrome (oculocerebrocutaneous syndrome) represent rhabdomyomatous mesenchymal hamartomas.28 Spontaneous regression has been documented.19,31
โข Genital type usually occurs in middle-aged women mainly in the vagina or cervix and only rarely in the vulva but may present in men most often in the spermatic cord, tunica vaginalis, and paratesticular soft tissue. The sclerosing variant seems to affect younger patients predominantly men.5โ10
โข The adult type typically arises in the head and neck region, mainly in the oral cavity and in soft tissue of the neck, and shows predilection for middle-aged or elderly males.2,5,11โ14 Occurrence in children is exceptional.15 Laryngeal and para or pharyngeal and esophageal lesions may occur.5,16โ22 Multifocal lesions are sometimes seen.5,23,24 Unusual sites include the lip and the extremities.25,26 Recurrence is exceptional.27
Histologic features The lesions are characterized by multiple bundles of mature striated muscle admixed with variable amounts of fat and fibrous tissue in the reticular dermis.
A case of multiple cutaneous lesions on the trunk of a child has been
documented.28 Recently, with the use of a monoclonal antibody specific for the cardiac isoform of ฮฑ-actin, it has been shown that extracardiac rhabdomyomas differentiate towards mature skeletal muscle while cardiac rhabdomyomas reflect true cardiac muscle differentiation.29
โข The fetal type presents in infants, with male predilection.3 The great majority occur on the face and neck, with particular predilection for preauricular or retroauricular and periorbital regions. Involvement of the upper respiratory tract and intraoral lesions may also occur.30,31 Other sites include chest, abdomen, pelvis, and extremities.5 Genital lesions are exceptional.32,33 There is an association with nevoid basal cell carcinoma syndrome.34,35 A case associated with tuberous sclerosis has been reported.36 Most tumors involve children less than 1 year of age and some are congenital. Occurrence in older children is very rare.32 Cutaneous case have been described.37,38
Differential diagnosis Distinction from accessory tragus can be made by the usual acral clinical location, histologic absence of striated muscle and the presence of cartilage in the latter condition.