Uterine mesenchymal tumours are a heterogeneous group of neoplasms that can frequently be diagnostically challenging [1]. The most common benign and malignant tumours are leiomyoma and leiomyosarcoma respectively [2]. Leiomyoma is a benign neoplasm composed of smooth muscle cells with a variable amount of fibrous stroma,most commonly affects the body of the uterus [3,4].

It is present in 20-30% of women over 30 years of age rising to more than 40% in those over 40 years old [4,5,6]. Prevalence of fibroids increases to more than 70% with pathological examination of the uterus, indicating that many women who have fibroids are asymptomatic [7].

Most subtypes of leiomyoma are chiefly of interest in that they mimic malignancy in one or more respects [3]. Diverse histological features of uterine leiomyomas are responsible for an erroneous diagnosis of malignancy [8]. Difference between the benign and malignant counterparts of mesenchymal tumours is significant due to the differences in the clinical outcome and the role of the surgical pathologist in making this distinction (especially in difficult cases) cannot be underestimated [1].

Setting and type of study: This study was undertaken in the Department of Pathology, JJM Medical College, Davangere. It was prospective study. The study period of two years from July 2010- June 2012.

Sampling method: Material for the study consisted of hysterectomy specimens & myomectomy specimens which were sent for histopathological examination to the Department of Pathology, JJM Medical College from Bapuji Hospital, Chigateri General Hospital and also from private hospitals in and around Davangere. Relevant clinical data was collected from the hospital and laboratory records.

The specimens were received in 10% formalin; after adequate fixation were subjected to thorough gross examination and appropriate sections were taken. After tissue processing, multiple 4-6µ thick paraffin sections were stained with hematoxylin and eosin.

Sample size: Among 12,285 surgical specimens received for histopathological examination in the Department during the study period.

Variants of leiomyoma: Variants of leiomyomas were seen in 8 cases constituting 1.68% of all leiomyomas. Of these, 4 cases were lipoleiomyoma, 2 atypical leiomyoma, one cellular leiomyoma and one apoplectic leiomyoma.

1. Lipoleiomyoma: 4 cases of lipoleiomyomas were seen between 5^th & 6^th decades of life. 3 patients presented with mass per abdomen and one with menstrual disturbance (table I). These tumours measured 3-6cm in their greatest dimensions and were intramural and subserosal in location. One of the tumours showed gross evidence of lipoleiomyoma (Figure 2).

Table-1: Details of cases of lipoleiomyoma.

Figure 2: Sectioned surface of uterine lipoleiomyoma showing distinct pale yellowappearance one side and a subserosal leiomyoma on the other side

Microscopically, the tumours were composed of admixture of varying amounts of mature adipose tissue with smooth muscle cells (Figure 3). The adipose tissue was scattered and at places diffusely distributed within leiomyomas.

2. Atypical leiomyoma: Was diagnosed in two cases, (table II)Cut section of tumour in both the cases was grey white with whorled appearance.

Table 2: Details of cases of atypical leiomyoma.

Microscopic sections from both the cases showed smooth muscles with moderate to severe cellular atypia arranged in fascicles with areas of smooth muscles with markedly pleomorphic and enlarged nuclei (nuclear atypia appreciated at lower magnification) (Figure 4). Clusters of bizarre hyperchromatic and multinucleated smooth muscle cells were seen. Also noted degenerative cells, smudged chromatin and intranuclear vacuolation. Occasional mitoses (2-3/10 HPFs) were noted. Necrosis was absent.

3. Haemorrhagic cellular (apoplectic) leiomyoma: A case of haemorrhagic cellular leiomyoma was diagnosed in a 43yr old female who presented with mass per vaginum. On gross examination, tumour showed a polypoidal mass in the endometrial cavity measuring 5x3cm with foci of hemorrhage. Microscopically, the tumour was cellular, with closely packed round to spindle cells with scanty cytoplasm. There was no cytologic atypia. Blood vessels were large with thick muscular wall and cleft like spaces seen. Patchy areas of haemorrhage and oedema were made out. Also noted scattered lymphocytes and hemosiderin macrophages. Occasional MFs (<2/10 HPFs) were seen. The tumour appeared to merge with the surrounding myometrium.

Cellular leiomyoma: A case of cellular leiomyoma was diagnosed in a 40yr old female who presented as mass per abdomen. Two intramural leiomyomas were made out on gross examination, larger measuring 4cm in diameter which was soft in consistency and showed areas of mucoid change on cut section and the smaller one measured 3cm in diameter which showed regular whorled appearance on cut section.

The tumour should be examined thoroughly, and one block of tissue should be taken for each centimeter of tumour diameter, except from grossly typical leiomyomas; even the latter may have to be examined extensively if the microscopic appearance is unusual [5]. Variants of leiomyomas were seen in eight cases constituting 1.68% of all leiomyomas. Of these, four cases were lipoleiomyomas, two atypical leiomyoma, one cellular leiomyoma and one apoplectic leiomyoma.

1. Lipoleiomyoma: Lipoleiomyoma is a rare entity which should be differentiated from liposarcoma. Four cases of lipoleiomyoma were diagnosed constituting to 0.84% of all leiomyomas (table III). On gross examination inaddition to white whorled appearance yellowish discoloration was seen. On microscopy interlacingbundles of smooth muscles were mixed with matureadipocytes.

Table-III: Comparison of incidence of lipoleiomyoma in various studies.

Table-IV: Comparison of age incidence of lipoleiomyoma in various studies.

The mean age of occurrence of lipoleiomyoma in the present study was found to be in 5^th decade (table IV)

2. Atypical leiomyoma: Important entity as it can be misdiagnosed asleiomyosarcoma (Figure-3). It is characterized byspindle cells along with scattered multinucleatedbizarre cells with prominent nucleoli that may mimicatypical cells[13]. A study by Philip PC et al stated that the term atypical leiomyoma is considered if the tumour showed focal or multifocal moderate to severe atypia, and no tumour cell necrosis [14]. Similar features were seen in the present study.

Average rate of mitoses of 2-3/10HPFs noted in the present study also correlated with the study by Oliva E et al [15].

Nonetheless, the bottom line is that, at the present time, the diagnosis of a leiomyoma variant cannot be made with certainty until a pathologist, guided by recently updated 2014 World Health Organization criteria [10], thoroughly examines the specimen.

Nischita Budihal: Data collection, analysis Conceptualization, literature search &writeup. Jayashree G Pawar: Designing the study and supervised the study. Manasa G C: Manuscript preparation and proof reading.