Resident Forum
An Asymptomatic Erythematous Plaque on the
Chin of a 45-year-old Woman
Ching-Po Wang Cheng-Chieh Hsu Yu-Hung Wu Yang-Chih Lin
CASE REPORT
A 45-year-old woman had asymptomatic skin lesions for several months. She was healthy except
for a history of hyperthyroidism 10 years previously treated with thyroidectomy. She then became
hypothyroid and had been maintained on thyroxine replacement. She had no congenital anomalies and
her family history was non-contributory. Physical examination revealed a slightly erythematous, nontender plaque on the chin (Fig. 1). She had areas of induration and non-pitting edema on her shins and
upper back. The results of blood tests, including thyroxine and thyroid stimulating hormone, were within normal limits.
Myxedema was suspected, and a 4-mm punch biopsy specimen was obtained from the chin lesion.
Histologically, the dermis contained randomly oriented, mature, striated muscle fibers with admixed
mesenchymal elements including adipose tissue, vessels, and collagen (Fig. 2), findings consistent with
a diagnosis of RMH. The patient was offered CO2 resurfacing or excision, but she declined since the
plaque was benign and cosmetically inconspicuous.
Fig. 1
Fig. 2
A slightly erythematous indurated plaque on the chin.
(A) The dermis contains randomly oriented, mature, striated
muscle fibers with admixed mesenchymal elements. (H & E, x 40)
(B) Haphazardly arranged sebaceous lobules, adipose tissue,
and skeletal muscles in the reticular dermis. (H & E, x 100)
(C) Higher magnification shows the presence of skeletal
muscle bundles in the dermis. (H & E, x 400)
From the Department of Dermatology , Mackay Memorial Hospital
Accepted for publication: February 26, 2007
Reprint requests: Ching-Po Wang, Department of Dermatology, Mackay Memorial Hospital No. 92, Sec. 2, Chung-Shan N Rd.,
10449, Taipei, Taiwan
TEL: 886-2-2543-3535 ext. 2556 FAX: 886-2-2543-3642
Dermatol Sinica, Sep 2007
242
王靖博
DIAGNOSIS: Plaque Like Rhabdomyomatous Mesenchymal Hamartoma
DISCUSSION
RMH, also known as striated muscle hamartoma, hamartoma of cutaneous adnexa and mesenchyme, or congenital midline hamartoma, was
first described in 1986,1-3 with 34 cases reported to
date.1-9 It is most often congenital but can be discovered during adulthood either as a persistent
lesion since birth or as an acquired anomaly. The
most common presentation is as an asymptomatic
pedunculated nodule, like a skin tag, around the
eyes, nose, or mouth.
Only two of the previously reported 34 cases of RMH presented as plaques. One was that of
a 10-year-old girl with an asymptomatic, yellowish, ill-defined plaque for 4 years on her chin4 and
the other of a 40-year-old woman with an asymptomatic plaque on her chin for 10 years.5 Both
patients’ medical histories were unremarkable,
and there was no similar family history.
Histologically, RMH is characterized by a
normal epidermis overlying a dermis that contains
haphazardly oriented striated muscle fibers intermingling with varying amounts of mesenchymal
elements, including adipose tissue, blood vessels,
collagen, and elastic fibers. The differential diagnosis includes neoplastic or hamartomatous
tumors containing similar components. Cutaneous
rhabdomyoma, Triton tumors, and accessory tragus
may have skeletal muscle fibers. Rhabdomyoma
has embryonic skeletal muscle rather than mature
skeletal muscle fibers.7 Triton tumor, also known
as neuromuscular hamartoma, consists of subcutaneous nodules of skeletal muscle with intimately admixed neural elements.7 Accessory tragus
usually has elastic cartilage with only a few fragments of skeletal muscle near the base. Nevus
lipomatosis superficialis, fibrous hamartoma of
infancy, infantile myofibromatosis, and fibroepithelial polyp may have similar clinical and histological features but contain no skeletal muscle.6
Congenital RMH has been attributed to disordered development of second branchial archderived superficially located striated muscle, such
as the orbicularis oris, platysma, and orbicularis
243
oculi. The skeletal muscle fibers apparently
migrate aberrantly into the dermis during embryogenesis.7 Therefore, RMH is sometimes associated with other congenital abnormalities, such as
Delleman’s (oculocerebrocutaneous) syndrome.8
Case reports include a neonate with cleft lip and
palate, amniotic bands, and syndactyl upper
extremity digits,1 a neonate with bilateral leukocoria from sclerocornea, low-set ears and preauricular sinus,6 a 3.5-month-old infant with a
thyroglossal duct sinus,8 and a 6-month-old infant
with coloboma, corneal leukoma, microphthalmia, and a limbal dermoid.7
In summary, we report one additional case
of RMH, with a distinctive presentation as a
plaque. Although RMH is a benign lesion, it is
wise to consider the possibility of ocular or central nervous system anomalies when the condition
is congenital.
REFERENCES
1. Hendrick SJ, Sanchez RL, Blackwell SJ, et al.:
Striated muscle hamartoma: description of two
cases. Pediatr Dermatol 3: 153-157, 1986.
2. Grilli R, Escalonilla P, Soriano ML, et al.: The socalled striated muscle hamartoma is a hamartoma of
cutaneous adnexa and mesenchyme, but not of striated muscle. Acta Derm Venereol 78: 390, 1998.
3. Elgart GW, Patterson JW: Congenital midline
hamartoma: case report with histochemical and
immunohistochemical findings. Pediatr Dermatol
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adult. Kaohsiung J Med Sci 21: 185-188, 2005.
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Dermatol Sinica, Sep 2007