IMMUNOHISTOCHEMICAL ANALYSIS OF DIAGNOSED MELANOMA CASES IN AHMADU BELLO UNIVERSITY TEACHING HOSPITAL ZARIA (JANUARY 2005 - DECEMBER 2014)

Abstract

Introduction: This was a 10 year immunohistochemical analysis of all diagnosed melanoma
cases in the department of Pathology Ahmadu Bello University Teaching Hospital (ABUTH)
Zaria from January 1st 2005 to December 31st 2014.
Objectives: The study was aimed at confirming the diagnosis of melanoma over a ten year
period in the Department of Pathology, ABUTH Zaria, using immunohistochemical (IHC)
markers- S100, HMB45, Melan A and Vimentin, and to establish the immunohistochemical
profile of melanoma case in Zaria.
Materials and Methods: All morphologically diagnosed cases of melanoma from 1st January
2005 to 31st December 2014 formed the study material. All the relevant tissue blocks and
slides stained with Haematoxylin and Eosin (H&E) were retrieved from the departmental
records. IHC staining was done on stored paraffin embedded tissue blocks for a confirmatory
diagnosis of melanoma. The slides were studied with the supervising consultants.
Results: Eighty eight cases of melanoma were diagnosed in the department during the study
period. 72 cases met the study criteria. There were 26 males and 46 females with a male:
female ratio of 1.0:1.8. The ages ranged from 16 to 85 years with a mean age of 54 years. The
highest incidence was in the 6th decade of life. The foot was the commonest site with 38
(52.9%) cases, while 7 (9.8%) cases were seen in the rest of the lower limbs. There were 6
(8.2%) cases in the lymph nodes and 5 (6.8%) in the groin. Clark’s level was applicable to 61
(84.7%) cases. There were 4 (6.6%) cases in level III, 20 (32.8%) cases in level IV and 37
(60.7%) cases in level V. No cases were seen in levels I and II. Histologically, 46 (63.0%)
cases were distributed in sheets predominantly and 18 (25.0%) cases were in nests, while
pseudopapillary had 4 (5.6%) cases, trabecular had 3 (4.2%) cases and pseudoglandular had
only 1 (1.4%) case. Immunohistochemical staining showed S100 and Vimentin had 98.6%
positivity rates each, while HMB45 had 94.4% positivity rate and Melan A had 87.5%
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positivity rate. 62 (86.1%) cases were positive for all markers, 5 (6.9%) cases were positive
for a combination of vimentin, S100 and HMB45. Only 2 (2.8%) cases were positive for a
combination of vimentin and S100. A single case (1.4%) was positive for Vimentin.
Conclusions: Melanoma in Zaria showed a female predominance in life and the foot was the
commonest anatomic site of presentation. Majority of cases presented with advanced Clark’s
level IV and V disease. Immunohistochemistry showed S100 and Vimentin with highest
positivity rates. However in resource constraint settings such as ours, it is recommended that
S100 and either HMB45 or Vimentin will suffice in the immunohistochemical diagnosis of
melanoma.