An unusual multinucleated giant cell reaction in adenomyosis associated with treatment-refractory pain: A case report

Background: Adenomyosis is a common benign uterine condition typically associated with pelvic pain, heavy menstrual bleeding, and dysmenorrhea. While its histopathological features are well established, there are no well-documented English literature reports specifically characterizing multinucleated giant cell reaction (GCR) inside adenomyosis . Case presentation: A 43-year-old woman, gravida 1 para 1, presented with a 10-year history of progressively worsening pelvic pain that markedly impaired her quality of life. She was a known adenomyosis patient based on serial ultrasonographic examinations. She was treated with several medical therapies, including different progestogens (including dienogest for 9 months), repeated GnRH-analog injections, and escalating analgesics up to tramadol hydrochloride, without symptom relief. Her pain continued to worsen and eventually became unmanageable. After receiving Institutional Review Board (IRB) and insurance approvals, anesthesia clearances, and informed consent; she underwent a total abdominal hysterectomy with bilateral opportunistic salpingectomy. On gross examination, the uterus showed diffuse adenomyosis with areas of dark discoloration. Microscopic analysis confirmed adenomyosis with a striking GCR with haphazardly arranged nuclei surrounding brownish pigment deposits between smooth muscle fibers. No evidence of granulomatous disease was found. Remarkably, her pain disappeared completely after surgery, and she experienced a dramatic improvement in quality of life. Conclusion: This case appears to be the first to describe a multinucleated giant cell reaction (GCR) within adenomyosis. It broadens the known histopathologic features of adenomyosis and suggests that a chronic inflammatory response to repeated intramyometrial bleeding may play a role in severe, treatment-resistant symptoms. Recognizing this finding can help avoid diagnostic confusion and may encourage further research into inflammatory pathways involved in refractory adenomyosis.