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 Table of Contents  
Year : 2018  |  Volume : 21  |  Issue : 2  |  Page : 83-87

Vascular tumors in Northern Nigeria: A 10-year retrospective review

1 Department of Pathology, Aminu Kano Teaching Hospital, Bayero University, Kano, Nigeria
2 Department of Pathology and Forensic Medicine, University of Abuja, Abuja, Nigeria

Date of Web Publication6-Jul-2018

Correspondence Address:
Dr. Ibrahim Yusuf
Department of Pathology, Aminu Kano Teaching Hospital, Bayero University, PMB 3452, Kano
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DOI: 10.4103/smj.smj_63_16

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Background: Vascular tumors range from benign hemangiomas to lesions that are locally aggressive but infrequently metastasize, to relatively rare, highly malignant angiosarcoma. Objectives: The objective of this study is to determine the relative frequency and histologic pattern of these tumors in this locality and discover if any, differences in frequency and histopathological pattern from other centers. Materials and Methods: This was a 10-year retrospective study of all cases of vascular tumors diagnosed in the Department of Pathology, in a Teaching Hospital. Results: A total of 305 cases of vascular tumors representing 16% of soft tissue tumors were analyzed. The benign cases constituted 68% and the remaining were malignant. Lobular capillary hemangioma (40%) was the predominant benign histologic subtype recorded while Kaposi sarcoma constitute the most frequent malignant entity (21.6%). Head and neck was the most common site of affectation. Conclusion: Hemangiomas and Kaposi sarcoma was the most common benign and malignant vascular tumors recorded in this locality, respectively.

Keywords: Hemangioma, Kaposi sarcoma, tumors, vascular

How to cite this article:
Yusuf I, Solomon R, Atanda AT, Umar AB, Imam MI, Sule AA. Vascular tumors in Northern Nigeria: A 10-year retrospective review. Sahel Med J 2018;21:83-7

How to cite this URL:
Yusuf I, Solomon R, Atanda AT, Umar AB, Imam MI, Sule AA. Vascular tumors in Northern Nigeria: A 10-year retrospective review. Sahel Med J [serial online] 2018 [cited 2020 May 31];21:83-7. Available from: http://www.smjonline.org/text.asp?2018/21/2/83/236070

  Introduction Top

Vascular tumors range from benign hemangiomas to lesions that are locally aggressive but infrequently metastasize, to relatively rare, highly malignant angiosarcoma. These tumors can arise from the endothelium (e.g., hemangioma, lymphangioma, and angiosarcoma) or from cells that support and/or surround blood vessels (e.g., glomus and hemangiopericytoma).[1] The classification of vascular tumors and ectasias is far from straight forward. There is difficulty in separating true neoplasm from reactive proliferation or developmental abnormalities. Second, some vascular tumors represent dilatation of preexisting vessels rather than a proliferation of new blood vessels.[2] It also remains essentially impossible to reliably distinguish blood vessel endothelium from lymphatic endothelium,[2],[3] which probably reflects the common functional and embryonic relationship between these two cell types.[3] There is a paucity of studies on vascular tumors in Nigeria, and all the reports are hospital based. Although population-based studies are required to know the true incidence and specific features of vascular tumors in Nigeria, this yet another hospital based study, will be useful in determining the relative frequency and patterns of these tumors in this locality and discover, differences in frequency and histopathological pattern from other centers where such studies have been conducted. The study will also pave the way or set the stage for more comprehensive population-based reviews that will highlight the true incidence of these tumors in Nigeria.

  Materials and Methods Top

The study was a 10-year retrospective review of all cases of benign and malignant vascular tumors diagnosed in the Department of Pathology, Aminu Kano Teaching Hospital from January 2004 to December 2013. The hematoxylin and eosin (H and E) stained slides were retrieved from archive and reviewed by the authors. Fresh H and E stained sections were made from archived paraffin-embedded tissue blocks to replace broken or missing slides. Special stains such as reticulin were used to demonstrate vascular basement membranes. The request forms were retrieved, and relevant clinical data such as the age, gender, site of affectation, and histological diagnoses were obtained. The tumors were classified into benign, intermediate, and malignant in accordance with the WHO classification and the result analyzed using simple frequency distribution and presented in tabular form. Ethical approval was obtained on 16th February 2016 from the Ethics and Research Committee of Aminu Kano Teaching Hospital, Kano.

  Results Top

A total of 44, 566 surgical specimens were received over the 10 year review period among which were 1906 (4.3%) cases of soft tissue tumors. Of the total number of soft tissue tumors that were recorded, 305 (16%) were vascular tumors.

The 305 patients with vascular tumors comprised of 161 males and 144 females with a sex ratio of 1.1:1 [Table 1]. Benign lesions (68%) comprised of the majority of the tumors diagnosed. Among the benign cases, lobular capillary hemangioma was the most frequent with 123 (40.3%) cases followed by pyogenic granuloma with 33 (10.8%) cases.
Table 1: Sex Distribution of Vascular Tumours

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Malignant cases constituted 32% of the tumors reviewed. Kaposi sarcoma (21.6%) had the highest frequency comprising of 66 cases while angiosarcoma comprised of 22 (7.2%) cases. The least diagnosed lesions were Hemangioendothelioma and hemangioblastoma with 3 (2.30%) and 1 (0.33%) cases, respectively [Table 2].
Table 2: Age distribution of vascular tumors

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Majority of the tumors occurred in the second and third decades of life and the frequency then showed a gradual decline in the seventh decade. The least recorded cases occurred in the sixth decade. Hemangioma occurred predominantly in the first 3 decades of life while Kaposi sarcoma occurred predominantly in the fourth decade [Table 2].

As depicted in [Table 3], 58 (19%) cases involved the head and neck region excluding the oral and nasal cavities, lips, and conjunctiva which recorded 30 (9.8%), 23 (7.5%), 27 (8.9%), and 10 (3.3%), respectively. The upper and lower limbs were involved in 16.3% and 16.1%, respectively, with Kaposi sarcoma predominantly seen in the lower extremity. Genital region is the least affected site with 8 (2.6%) cases.
Table 3: Site distribution of vascular tumors

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  Discussion Top

A total of 305 cases of vascular tumors were diagnosed over the 10 years study period. This represents an average of approximately 30 cases/annum and is the largest recorded yearly average in similar Nigerian studies. The local yearly averages from Zaria,[4] Lagos,[5] Maiduguri,[6] Benin,[7] Illorin,[8] and Port Harcourt [9] are 13, 19, 14, 11, 18, and 12 cases/annum, respectively. The relatively higher annual average inour centre probably reflects the comparatively larger volume of samples received.

Benign vascular tumors constituted 68% while intermediate and malignant tumors accounted for 25% and 7%, respectively. Benign tumors were the majority in all of the available local studies [4],[5],[6],[7],[8],[9] and this agrees with the findings of this study.

The mean age at diagnosis was 29 years and 60.3% of these tumors occurred in children and young adults aged 0–30 years. Both figures are in concordance with the findings of Obaseki [7] in Benin who recorded a mean age of 27.9 years and 60.5% affecting children and young adults, respectively. Adults accounted for 87.7% of the tumors both benign and malignant while children aged 0–14 constituted 22.3% and this is similar to findings by Ojo et al.[8] in Ilorin.

The tumors exhibit a very slight male predominance with a male:female ratio of 1.1:1. It is noteworthy that most of the Nigerian studies including that of Rafindadi and Malami,[4] Malami and Banjo,[5] Ojo,[8] and Seleye-Fubara and Nwosu [9] similarly showed either a slight male or female predominance. However, Ngadda et al.[6] in Maiduguri reported a significant male bias.

The head and neck region with or without the inclusion of the oral and nasal cavities, lips, and conjunctiva, remains the most frequently affected body region by hemangiomas. This is established in this study and other references. Significant numbers of hemangiomas (capillary, cavernous, and pyogenic granulomas) were seen to involve the oral and nasal cavities, lips, and conjunctiva.

Hemangiomas are tumors characterized by increased numbers of normal and abnormal vessels filled with blood. A high proportion of these tumors occur in children and many are already present at birth.[3],[10] Hemangiomas of various histological types (Capillary, cavernous and pyogenic granuloma) form the bulk of the tumors studied and constituted 60.9%. Most hemangiomas are solitary and over half of the cases involve the head and neck region.[7],[10] Capillary hemangioma is the most frequent lesion of all the vascular tumors studied (40.3%). This tumor has demonstrated a predilection for head and neck region and structures therein, especially the lips, nasal, and oral cavities where it records the highest occurrence in this study and a tendency to affect children and young adults. These features are in concordance with the findings in Zaria,[4] Lagos,[5] Maiduguri,[6] Benin,[7] Ilorin,[8] and Port Harcourt.[9] Pyogenic granuloma had the least frequency of affectation among the hemangiomas and is reported more in the head and neck region. This tumor has a peculiar predilection for oral cavity of pregnant women.[11]

Lymphangiomas represents malformations rather than true neoplasms and are thought to result from failure of the lymphatic system to communicate with the venous system.[10] They are common pediatric lesions, which are most often present at birth or during the 1st years of life. Sites of involvement include the neck, axilla, groin, oral cavity, trunk, and limbs.[3] Lymphangiomas constituted 4.6% of the vascular tumors studied and 86% of this lesion presented within the first 2 decades of life. Head and neck region is the most frequent site affected. Similar findings have been documented by Rafindadi and Obaseki in Zaria, and Benin, respectively.[4],[5]

The two perivascular tumors encountered in this study are glomus tumor and hemangiopericytoma. Glomus tumor is rare, accounting for >2% of soft tissue tumors.[3] In this study, they accounted for 2% of vascular tumors. In Benin,[7] only a case (0.6%) of glomus tumor was found, and the other available local studies [4],[6],[8] documented no cases. Similarly, a study by Harris [12] at the Mayo clinic highlighted the rarity of this tumor as it accounted for only 1.6%. This tumor occurs in distal extremities, particularly the subungual region, the hand, the wrist, and the foot.[3],[9] All the 6 cases of glomus tumor seen in this study were located in the upper limb, specifically in the subungual region of the digits. Hemangiopericytoma is a term which has been used to loosely encompass a wide variety of neoplasms which have in common the presence of thin-walled branching vascular pattern. The delineation of hemangiopericytoma as a separate entity may become obsolete since its histological features are shared by a variety of soft tissue tumors.[13] Adults are predominantly affected. We recorded 7 cases (2.3%) of hemangiopericytoma including two occurring in individuals less than (<)10 years of age.

Hemangioblastoma comprises of 1%–2% of all intracranial tumors. These tumors commonly develop in the cerebellum of adults in their third and fourth decades, but they can rarely occur in infants and children. Most cases arise in the posterior fossa.[11] A case of hemangioblastoma was encountered in this study occurring in a 15-year-old girl and sited in the posterior fossa.

Kaposi sarcoma is the most frequent malignant tumour recorded by this study and comprised of 21.6% of the vascular tumors reviewed. This is an endothelial tumor that presents with cutaneous lesions in the form of multiple patches, plaques, or nodules. Four different clinical and epidemiological types are recognized: classic type seen in elderly men of Mediterranean/east European descent, endemic African type in non-HIV infected adults and children seen in equatorial Africa, iatrogenic type appearing in solid organ transplant patients, and AIDS-associated type seen mainly in homosexual and bi-sexual men.[14] The tumor is uniformly associated with human herpesvirus type 8 and the skin is commonly affected, but lymph nodes, viscera and mucous membranes may be involved.[2] This review recorded Kaposi sarcoma accounting for 67.3% of the malignant vascular tumors and predominantly affecting the skin of the lower limb. This is in agreement with the findings of Rafindadiand Malami [4] and Obaseki [7] where Kaposi sarcoma was also the most common malignant histological type. The highest number of affected individuals were observed in the fourth decade in concordance with an earlier study by Yusuf et al.,[15] stressing the fact that in this environment, this tumor is seen commonly in young adults and associated with HIV.[16]

Hemangioendothelioma is a rare vascular tumor occurring in nearly all age groups and affects both sexes equally.[17] In keeping with the rarity of this tumor, only 3 (1%) cases were recorded. Similar results were obtained in the Maiduguri [6] and Benin [7] reviews where this tumor constituted 1.2% and 0.7%, respectively.

Angiosarcoma of the soft tissue is rare sarcomas which develops mainly as cutaneous tumors and less than a quarter present as deep soft tissue masses.[18] The peak incidence is in the seven decade, and it is rare in children.[19] Twenty-two cases (7.2%) of angiosarcoma were seen in this review with only a case affecting a child. There is the relatively higher frequency for this tumor recorded in this center compared to Lagos,[5] Benin,[6] and Ilorin [8] where this tumor accounted for 1.2, 0.8, and 1%, respectively. This might be due to the larger sample size of this study. The tumor is seen mainly in adults with peak incidence in the sixth decade.

  Conclusion Top

Vascular tumors form a significant proportion of soft tissue tumors recorded by this study with benign cases being more common than their malignant counterpart. The benign subtypes are more commonly seen in children where they are predominantly located in the head and neck region. Capillary hemangioma represents the most common benign vascular tumor while Kaposi sarcoma is the most frequent malignant vascular tumor.

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Conflicts of interest

There are no conflicts of interest.

  References Top

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Rosai J. Soft tissue. In: Rosai J, editor. Rosai and Ackerman's Surgical Pathology. 9th ed. Ch. 25. Philadelphia: Mosby; 2004. p. 2285-6.  Back to cited text no. 10
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  [Table 1], [Table 2], [Table 3]


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