What is the incidence and treatment of leiomyosarcoma in young girls?

Incidence and Treatment of Leiomyosarcoma in Young Girls

Leiomyosarcoma is extremely rare in young girls, with an incidence of less than 2 per 1,000 per year, and treatment should focus on wide surgical excision with negative margins as the primary intervention. 1

Epidemiology and Incidence

Leiomyosarcoma (LMS) is exceedingly uncommon in the pediatric population:

• Soft tissue sarcomas as a group have an overall incidence of 4-5/100,000/year in Europe 1
• Leiomyosarcoma specifically has an incidence of less than 1/100,000/year 1
• In children, leiomyosarcoma represents an even smaller fraction of these already rare tumors
• Most leiomyosarcomas occur in adults, particularly in perimenopausal and postmenopausal women 2
• When occurring in children, there is no significant gender predilection (11 girls and 9 boys in one series) 3

Clinical Presentation in Young Girls

When leiomyosarcoma does occur in young girls, it typically presents as:

• Small, localized tumors in soft tissues 3
• Most commonly affecting:
  • Trunk (30%)
  • Head and neck (25%)
  • Lower limbs (25%)
  • Upper limbs (20%) 3
• Median age of 12 years (range 4-15 years) in pediatric cases 3
• Median tumor size of 2.5 cm (range 0.5-13 cm) 3
• Rare cases of primary gastric leiomyosarcoma have been reported in adolescents 4

Pathological Features

Pediatric leiomyosarcomas have distinct pathological characteristics:

• Majority (85%) are low-grade tumors 3
• Show typical features of smooth muscle differentiation with fascicles of eosinophilic spindle cells with cigar-shaped nuclei 3
• Immunohistochemically positive for:
  • Alpha-smooth muscle actin (89%)
  • HHF-35 (87%)
  • Desmin (61%) 3
• Histologic criteria for malignancy include increased mitoses, cellular pleomorphism, and thrombotic degeneration 1, 2

Treatment Approach

The treatment of leiomyosarcoma in young girls should follow these principles:

1. Surgical Management:

   • Wide local excision with negative margins is the mainstay of treatment 3, 5
   • Complete resection with negative microscopic margins is critical for prognosis 6
   • For visceral leiomyosarcoma (e.g., bladder), organ-preserving surgery such as partial cystectomy may be appropriate 7

2. Adjuvant Therapy:

   • Radiation therapy may be considered for:
     • Incompletely resected tumors
     • High-grade lesions
     • Recurrent disease 6
   • Chemotherapy options include:
     • Doxorubicin-based regimens
     • Cisplatin-based regimens 6
   • For unresectable cases, combined chemotherapy and radiation therapy may provide disease control 7

Prognosis and Follow-up

Pediatric leiomyosarcoma has a distinct prognostic profile:

• Generally more favorable than adult leiomyosarcoma 3
• Relatively indolent behavior in most pediatric cases 3
• 5-year overall survival rate of approximately 79% 6
• 10-year survival rate decreases to approximately 49% 6
• Late recurrences can occur, even beyond 10 years 6
• Important prognostic factors include:
  • Tumor grade (high-grade tumors have worse prognosis)
  • Surgical margins (complete vs. incomplete resection)
  • Tumor size 6

Special Considerations

• Multidisciplinary approach involving pediatric oncologists, surgeons, radiation oncologists, and pathologists is essential 1
• Treatment should be carried out in reference centers for sarcomas with expertise in pediatric oncology 1
• Long-term follow-up is critical due to the risk of late recurrences 6
• Differential diagnosis includes infantile myofibromatosis, leiomyoma, monophasic synovial sarcoma, and spindle cell rhabdomyosarcoma 3

Genetic Considerations

In rare cases, leiomyosarcoma may be associated with genetic syndromes:

• Hereditary leiomyomatosis and renal cell cancer (HLRCC) syndrome due to FH gene mutations 1
• Annual skin examinations are recommended for children with FH mutations to assess for cutaneous leiomyomas and changes suggestive of leiomyosarcoma 1

While leiomyosarcoma is extremely rare in young girls, awareness of its clinical presentation, appropriate diagnostic workup, and treatment principles is essential for optimal outcomes in these challenging cases.