Case Report:
An 11-year-old Caucasian female presented with a <5cm firm,
left sided, non-tender neck mass for a month, with no constitutional
symptoms. She was initially treated with a course of antibiotics for
suspected lymphadenitis with no response. Following surgical resection,
histopathology revealed that the tumor is composed of admixture of
spindle and ovoid cells (Fig. A1&2). Rare mitosis was seen (Fig. A3). A
panel of immunostains was performed and showed a strongly positive
caldesmon and weakly positive smooth muscle actin; supporting the
diagnosis of low grade leiomyosarcoma with positive microscopic margins.
Her CT chest was negative for metastatic disease and PET scan showed
mild FDG avidity in left side of the neck – level IIb node - with no
other areas of PET avidity. Concerned with the microscopic margins, a
second surgery was performed, but continued to show microscopic margins.
She was finally staged as Stage I (G1, T1b, N0, M0 disease) by the AJCC
guidelines. We opted for no further treatment as a third surgery seeking
negative microscopic margins will be disfiguring with unclear benefit.
Furthermore, radiation has been associated with long-term consequences
with unclear benefit to a patient with low risk disease. She is closely
monitored with serial imaging. MRI and PET CT performed at 3 and 6 month
interval has not shown evidence of local disease.
The unusual presentation of leiomyosarcoma in our patient led to
molecular analysis of her tumor with next generation sequencing (NGS)
showed chromosomal re-arrangement involving FGFR1-TACC1 and copy number
loss of MTAP, CDKN2A, and CDKN2B on array CGH