Tracing the Journey of Endometrium, from Womb to Arm: Deltoid Endometriosis

BACKGROUND: Endometriosis is an enigma. Extrapelvic endometriosis is even more challenging, as theories of origin are difficult to explain. Very few cases of skeletal endometriosis have been reported in the literature. METHOD: We managed a case of 39-year-old nulliparous woman, who presented to the department of plastic surgery with complaints of a painful nodule measuring about 2 cm, in left upper arm since past 8 years. She had history of myomectomy 8 years back, while she was undergoing treatment for primary infertility. Differential diagnosis of extrapelvic endometriosis was made based on clinical history of cyclical pain and swelling, and she was referred to gynecology for hormonal treatment. MRI and FNAC were inconclusive. She underwent excision biopsy of the lesion. RESULT: Histopathology confirmed intramuscular endometriosis of left deltoid with positive margins. Postoperatively, she was started on dienogest 2 mg once daily and LNG IUS was inserted. Both were withdrawn a year later, due to side effects. It has been more than 6 months since removal of LNG IUS, and currently she is asymptomatic. CONCLUSION: To the best of our knowledge, this is the third case of deltoid endometriosis reported till date.