PMC9363927_01
CT scan shows a lobulated 1.6 cm vascular mass in the pronator quadratus muscles along the interosseous membrane near the distal radioulnar joint.
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At follow-up two years later, a subtle palpable wrist mass was present, and an MRI revealed a 3.4 x 1.6 x 2.5 cm multiseptated cystic volar soft tissue mass along the interosseous membrane within the pronator quadratus muscles (Figure 1).
Histology (40x) shows a central cluster of thin-walled vessels, adjacent small lymphoid aggregate, focal adipose tissue, and a large vessel with a thick muscular wall.
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Histologically, the tumor was an intramuscular vascular malformation composed of fibroadipose tissue, thin-walled vascular channels, abnormal large veins with muscular walls, and associated lymphoid aggregates (Figure 2).
Next generation sequencing results demonstrate a low allele frequency c.3140A > G (p.His1047Arg) mutation of the PIK3CA gene. Reference amino acids and coding nucleotides are indicated at the bottom. Gray bars represent wild-type sequence.
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The only significant alteration found was a pathogenic His1047Arg mutation in the PIK3CA gene (Figure 3; read depth 15,576x).