A 54-year-old Japanese female with polyarteritis nodosa was admitted to the
hospital. She developed lower abdominal pain accompanied by melena. A pene
trating ulcer and extensive hemorrhaging were endoscopically observed in th
e sigmoid colon, and a sigmoidectomy was performed. The pathologic findings
were a granuloma formation with lymphocytic infiltration and luminal occlu
sion of branches of the mesenteric arteries. Although the gastrointestinal
tract is frequently involved in polyarteritis nodosa, the colon is rarely a
ffected. To our knowledge, this is the first report of polyarteritis nodosa
causing a penetrating ulcer of the colon.