Pseudo-invasive, vasculocentric adenomyosis is a rare benign condition of the uterus, characterized by the pathological presence of variable sized, non-neoplastic endometrial glands surrounded by endometrial stroma deep within the myometrial blood vessels [1].

Over the past years, the disease was seen in multiparous women in their fourth and fifth decade, with other risk factors being prior caesarian surgery or uterine surgery [2,3]. Advanced imaging techniques may be a help to diagnose pseudo-invasive adenomyosis in young women [4,5]. However, microscopic examination of hysterectomy specimens still remains the gold standard to make a definitive diagnosis of pseudo-invasive vasculocentric adenomyosis [6].

The majority of patients affected present with abnormal uterine bleeding, pelvic pain, dysmenorrhea, dyspareunia, or infertility while a third of them may be asymptomatic [7,8]. Adenomyosis often coexist with other hormone dependent disease entities such as endometriosis or uterine fibroids [9].

Adenomyosis is described as a distinct entity in the PALM-COEIN FIGO (polyp; adenomyosis; leiomyoma; malignancy and hyperplasia; coagulopathy; ovulatory dysfunction; endometrial; iatrogenic; and not yet classified – International Federation of Gynecology and Obstetrics) classification [10].

The junctional zone is the site of origin of cycle dependent contractions seen at various phases of the menstrual cycle [11]. Disturbances in these contractions leads to repeated trauma to the junctional zone, resulting in invasion of myometrium by the basal layer of the endometrium through this altered hormone responsive zone [12]. This theory explains the risk factors (multiparity, prior uterine surgery) related to the development of adenomyosis [11,12]. Another hypothesis suggests metaplastic changes in the myometrial stem cells to play a role in disease development [13].

Adenomyosis presents with non-specific symptoms, also seen in other gynaecological disorders. Chronic pelvic pain is common which may be mediated by prostaglandin [14]. Various studies have demonstrated a significant correlation between the depth of adenomyosis and the severity of abnormal uterine bleeding (AUB) [15,16].

The clinical differential diagnosis for intra-myometrial lesions includes includes leiomyoma, adenomyoma/ adenomyosis, hematoma, atypical adenomyoma, sarcomas and endometrial carcinoma [17,18]. The histologic findings of benign endometrial glands and stroma misplaced within smooth muscles are typical of adenomyosis [19]. The present case is morphologically exceptional, in having a pseudo-invasive, predominantly vasculocentric growth pattern of adenomyosis.

Whether adenomyosis occurs secondary to de novo, non-neoplastic intrusion of endometrium via caesarean surgery lacunae, or it reflects a developmental anomaly, or is of stem cell origin – is debatable, but the vasculocentric predilection displayed by the present case is even more intriguing. Given it’s rarity, it is well worth remembering this entity, when countenanced with uterine intra- myometrial infiltrative appearing lesions, that do not ‘quite fit’, clinically or morphologically.