CLASSIFICATION OF UTERINE SMOOTH MUSCLE NEOPLASMS IN LUTH, LAGOS, NIGERIA: AN AUDIT OF PRACTICE

Abstract

Background: Uterine smooth muscle neoplasms are defined as benign or malignant neoplasms
composed of cells demonstrating smooth muscle cell differentiation. Uterine leiomyomata, also
known as fibroids, are the benign forms and they are the commonest. The main clinical purpose
of histopathological classification and staging of uterine neoplasm is to prognosticate on the
likelihood for the development of local relapse or metastasis.
Aim/objective: To evaluate the adequacy of sampling and reclassify uterine smooth muscle
neoplasm diagnosed between 2009-2013 while comparing the findings with cases seen in 2014.
Materials and methods: This study was conducted in the department of Anatomic and
Molecular pathology, Lagos University Teaching Hospital, Lagos in Southwestern Nigeria. It
was descriptive and comparative. Uterine smooth muscle neoplasms diagnosed in LUTH
between 2009-2013 were re-examined and described using WHO criteria for the classification of
uterine smooth muscle neoplasms. Immunohistochemistry was performed on selected malignant
cases. Uterine smooth muscle tumour samples for 2014 were also grossed and examined using
standard criteria for handling such specimen and a comparison was made between the two
groups.
Results: Following reclassification of the tumours, majority were still benign, with 207 (90.1%)
renamed as leiomyoma, not otherwise specified, (using the WHO terminology). This is close to
proportion previously signed out with the terminologies uterine leiomyoma/leiomyomata and
degenerated leiomyoma/leiomyomata (91.3%). This study also showed that 3 out of 8 cases
previously diagnosed as leiomyosarcoma were 2 cases of malignant mixed mullerian tumour and
a case of endometrial stroma sarcoma. One of the cases was also a bizarre leiomyoma and not
leiomyosarcoma as previously diagnosed. There is no statistically significant difference in the

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diagnosis made when numerous blocks are submitted in cases where there are numerous tumour
nodules and when fewer blocks are submitted (p = 0.58). When sections from all tumour nodules
received in 2014 were submitted, cases that appeared benign on gross examination also remained
benign when examined microscopically despite the rigours of sampling, submitting and
examining all nodules which in some cases were as many as fifty eight. The only malignant case
seen in 2014 already had features of malignancy on grosss inspection and this was confirmed by
both H&E morphology and immunohistochemistry.
CONCLUSION/RECOMMENDATION: This study showed that some other types of uterine
malignancies were wrongly classified as leiomyosarcoma and this can have significant impact on
management of patients. Immunohistochemistry will help avoid such error in future. The study
also shows that adequate sampling to avoid missing out malignant cases does not depend on
submitting numerous cassettes but rather on the ability of the pathologist to skillfully identify
grossly abnormal areas and submit blocks from such areas.