MR"I": An "eye" for the preoperative diagnosis of ectopic molar pregnancy, a case report

Hydatidiform mole (complete and partial), invasive mole, choriocarcinoma, placental site trophoblastic disease, and epithelioid trophoblastic tumour constitute the spectrum of benign and malignant gestational trophoblastic disease[1] Invasive mole, choriocarcinoma, placental site trophoblastic disease, and epithelioid trophoblastic tumour also classify under gestational trophoblastic neoplasia.[1] The prevalence of molar pregnancy shows great worldwide variation with reported rates of 12 per 1,000 pregnancies in Indonesia, India, and Turkey; one to two per 1,000 pregnancies in Japan and China; and 0.5 to one per 1,000 pregnancies in North America and Europe.[1] Ectopic pregnancy, which is primarily tubal, is the leading cause of first trimester maternal mortality.[2] Diagnosis of ectopic pregnancy is a combinatorial analysis of clinical signs and symptoms; beta-hCG trends; and ultrasonography.[2] Since ectopic gestations cause maternal deaths, the decisive role of the diagnostic test employed measured by its discriminative potential for a reliable preoperative diagnosis is paramount.[2] Although ultrasonography demonstrates high sensitivity and specificity in diagnosing ectopic gestations, inconsistencies in sonographic identification have been known to occur.[2] Particularly, ultrasonography suffers from limitations such as specifying the exact location of infrequent extrauterine presentations and identifying ectopic gestations with atypical features.[2] Molar pregnancies that are largely known to be placental in location have a known but rare potential for extrauterine proliferation.[3] Ectopic molar gestations are rare with only more than a hundred reported cases in scientific literature.[4] Our case delineates this uncommon entity and the superiority of magnetic resonance imaging in terms of diagnostic performance in characterizing the gestational mass over ultrasonography. This is pertinent considering the need to differentiate an ectopic molar pregnancy from an ectopic pregnancy without molar tissue because the potential for malignancy in the former atypical form is akin to that of an intrauterine molar pregnancy.[4]