Introduction
Smooth muscle tumors of the female genital tract rarely occur outside the myometrium. Such tumors, when located in the immediate parametrial and para-adnexal connective tissues, have received scant attention, and little is known about their clinical and pathological features. 1 Microscopically parauterine tumors showed interlacing bundles of plump fusiform cells. 2 Osseous metaplasia of leiomyoma is an uncommon clinical entity with a presence of mature and immature bone in the leiomyoma. 3 Infection, necrosis, hyaline degeneration, calcification and myxoid degeneration are the most common secondary degenerative changes seen in cases of leiomyoma. Calcified and ossified leiomyomas are uncommon and rarely reported in literature. 4 We present a case of osseous metaplasia of leiomyoma occuring in bilateral broad ligaments.
Case Report
A 45 year old perimenopausal female was complaining of abnormal uterine bleeding. Obstetric history was notable for two spontaneous deliveries at term. Routine hematological and biochemical investigations were within normal limits. Ultrasound examination revealed a well defined round altered echogenic lesion, noted at fundus of uterus, measuring 10x7x4.5cm, suggestive of subserosal fibroid. She underwent total abdominal hysterectomy with bilateralsalpingo-oophorectomy. Grossly we received a specimen of uterus with cervix and bilateral adenexa, it measured 11x8x5cm, multiple calcified nodules were present in the broad ligaments on both sides, ranging from 0.5 to 1cm which were very hard and cut with difficulty. H and E stained sections from the nodules, revealed similar picture. Tumor was composed of hyalinised bundles of smooth muscles, areas of bony tabeculae with foci of ossification. Attached myometrium also revealed calcification. However there was no significant pleomorphism, nuclear atypia or mitosis. Patient had no metabolic calcium disorder, her serum calcium and phosphate were in the normal range, a histopathological diagnosis of osseous metaplasia with areas of calcification in hyalinized degenerated leiomyomas was given. Uterus, cervix with bilateral adenexa with multiple calcified nodules were present in broad ligament on both sides.
Discussion
Being one of the commonest tumor of female genital tract, the leiomyoma expectedly demonstrates a wide spectrum of histological variations. However, heterologous tissue differentiation is a rare finding and frank bone formation is even rarer. Leiomyomas are known to display a variety of histopathological variants,the usual type, cellular, mitotically active, atypical or plexiform, epithelioid and myxoid leiomyoma. 5 Calcification is rare and is seen only in 8% of the cases. Metaplasia occur as a result of reprogramming of stem cells or of undifferentiated mesenchymal cells, which differentiate along a new pathway. This differentiation is brought about by signals generated by cytokines, growth factors and extracellular matrix components in the cell’s environment. 6, 7 In most of the reported cases, the osseous changes in the leiomyomas were followed by a previous history of abortion. Majority of the patients are in the reproductive age group. The time interval between the antecedent abortion and discovery of ossification varies from 8 weeks to 14 years in reproductive age group. 8 The pathogenesis of ossification has been discussed by many hypothesis such as hypercalcemia, hypervitaminosis D, hyperphosphatemia, chronic endometritis, pyometra, persistent stimulation of endometrium by estrogen or osteogenesis in the surrounding endometrium which is promoted by retained fetal bones or dystrophic calcification part of the osteoblastic process. 9 The indexed case is also rare as patient had no such complaints. Role of estrogen has been found to have osteogenesis promoting effect. 10 Our patient was of perimenopausal age group, had only a history of abnormal uterine bleeding and her family was completed. So she agreed for hysterectomy. Adomsons & Somners reported a case of ossification in leiomyoma in a patient who was taking high dose of calcium and vitamin D for long time. No such history was found in our patient and our case had normal serum calcium and phosphate levels that rules out any such type of metabolic cause for ossification.11, 12
