【摘要】 报道罕见的老年患者的左眼眶横纹肌肉瘤1例，表现为严重的眼球突出及真菌样生长的肿块。一位66岁的马来女性，鼻衄8mo后出现左眼严重的突眼和真菌样生长的肿块。活检显示小泡型横纹肌肉瘤的组织学特征。
【关键词】 横纹肌肉瘤;成年人;眼眶
Rhabdomyosarcoma (RMS) comes from Greek words rhabdo means rod shape, myo means muscle. It was first described by Weber in 1854, but it was Stout who gave clear histological definition. They appear from primitive muscle cells[1].The ocular region particularly the orbital soft tissues represent a major anatomic location for RMS[2].
Orbital RMS is one of the few life threatening diseases seen initially by ophthalmologist and prompt diagnosis and treatment can save the life of the affected patient. RMS is the most common soft tissue sarcoma in the pediatric population. It accounts for 5%of all childhood cancer and for about 20%of all malignant soft tissue tumor The pleomorphic type occurs more often in adults but the embryonal and alveolar types mainly occur in infants and children. The head and neck RMS usually appear in the first decade of life.
The primary sites of RMS include head and neck area 45%, trunk 40% and extremities 15%, about 25%35% of head and neck RMS arise in the orbit. Several distinct histological groups have prognostic significance including embryonal RMS which occurs in 55% of patients whereas the botryoid variant occurs in 5% of patients, alveolar in 20% and undifferentiated in 20%. Treatment responses and prognosis vary widely depending on location and histology.
The cause of RMS is unknown. The alveolar variant is usually associated with one of two chromosomal translocations namely 2;13 or 1;13. These result in fusion of the DNA binding domain of the neuromuscular developmental transcription factors encoded by PAX3 on chromosome 2 or PAX 7 on chromosome 1. The resulting hybrid molecule is a potent transcription activator. It is believed to contribute to the cancerous phenotype by abnormally activating or repressing other genes.
Approximately 87% of patients are younger than 15 years and 13% are aged 1521 years. RMS rarely affects adults. Two peaks incidences tend to be associated with different locations; patients age 2 6 years tend to have head or neck or GU tract tumors, whereas adolescent 1418 years tend to have primary tumors in extremities, truncal or para testicular location.Prognosis can also be related to the size of tumors. Tumour size more than 5cm is associated with worse survival. Nodal involvement appears to be an adverse prognostic factor in both adult and pediatric RMS, while presence of metastasis is significantly associated with death[3].
CASE REPORT
A 66year old Malay lady presented with history of frequent heavy epistaxis from left nostril for about eight months associated with mild swelling of left eye. The proptosis gradually increased in size with complete loss of vision in left eye. Her general health was poor and there was significant loss of weight.
On ocular examination there is severe non axial proptosis of left eye with severe conjunctival chemosis and fungating mass lesion pushing the eye forward and downward (Figure 1). The vision in left eye was NPL and the orbit was frozen. Neck examination revealed bilateral palpable multiple lymph node masses at cervical and submandibular regions. The right eye was normal. A biopsy taken from the mass and histopathological examination showed RMS of alveolar type. CT scan showed a huge mass filling the left orbital cavity with some of the mass protruded outside the cavity. The left globe is pushed outside from its cavity and distorted in shape. The mass extends into nasopharynx with obliteration of both fossa of Rossenmuller and into left maxillary sinus and both nasal cavity, superiorly the mass infiltrates into the ethmoidal, sphenoida and frontal sinuses and involving the left temporal lobe, suprasellary region and cavernous sinuses especially on left side. (Figure 2).
The patient was started on cytotoxic chemotherapy into two phases. In phase one she received four cycles of Adriamycin 60mg, Vincristine 2mg and cyclophosphamide 1.2mg and in
Figure 1Severe fungating mass with non axial severe proptosis second phase she received four cycles of Mesna, Etoposide and Ifosfomide. Treatment was completed over 6 month duration. Subsequently the patient was lost to follow up.
DISCUSSION
RMS commonly affects children and young adult but extremely rare in elderly people. In adult population two third of tissue sarcoma arise in the extremities[4]. Orbital RMS comprise of 7% of all RMS [5] and accounts for 1%3% of biopsied orbital masses in all age groups and form 4% 6% of biopsied orbital masses in children.
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