|
 
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| ORIGINAL ARTICLE |
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| Year : 2020 | Volume
: 23
| Issue : 3 | Page : 170-178 |
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Histological spectrum of soft-tissue tumors in a tertiary hospital
Raymond Akpobome Vhriterhire, Joseph Aondowase Ngbea, Isaac Onah Akpor
Department of Anatomical Pathology, College of Health Sciences, Benue State University, Makurdi, Nigeria
| Date of Submission | 16-Aug-2019 |
| Date of Decision | 22-Jan-2020 |
| Date of Acceptance | 04-Mar-2020 |
| Date of Web Publication | 7-Oct-2020 |
Correspondence Address:
Dr. Raymond Akpobome Vhriterhire
Department of Anatomical Pathology, College of Health Sciences, Benue State University, Makurdi
Nigeria
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/smj.smj_39_19
Objective: The objective of this work was to determine the histological pattern of soft-tissue tumors diagnosed in our hospital and compare findings with those of other places. Background: A comprehensive record of the pattern of histologically diagnosed tumors is a fundamental requirement for good cancer screening policies, effective therapeutic decisions, and developing a regional cancer registry. The objective of this work was to determine the histological pattern of soft-tissue tumors diagnosed in our hospital and compare findings with those of other places. Materials and Methods: A retrospective audit of soft-tissue samples submitted in the histopathology laboratory of a tertiary hospital in Makurdi, North Central Nigeria, was carried out. Results: One hundred and eighty-eight soft-tissue tumors were diagnosed in the study period, and they had a male: female ratio of 1:1.2, with a mean age of 35.05 ± 18.9 years, and the most frequent occurrence in the fourth decade. Benign tumors were more common, 67.0% (n = 126), than malignant ones, 33.0% (n = 62). Lipoma accounted for the largest proportion of the tumors accounting for 38.9% (n = 49) of benign and 26.1% (n = 49/188) of all the soft-tissue tumors. Embryonal rhabdomyosarcoma was the most frequent malignant tumor, with peak occurrence in the first decade, and comprised 25.8% (16/62) of the malignant soft-tissue tumors and 8.5% (n = 16/188) of all soft-tissue tumors. Kaposi sarcoma, a tumor of intermediate malignancy, consisted of 24.2% (n = 15/62) of the malignant soft-tissue tumors. The remaining malignant soft-tissue tumors found in this study included pleomorphic rhabdomyosarcoma, alveolar rhabdomyosarcoma, liposarcoma, angiosarcoma, pleomorphic sarcoma, malignant fibrous histiocytoma, and hemangiopericytoma. Conclusion: Lipoma was the single most common soft-tissue tumor. Half of all the malignant tumors consisted of embryonal rhabdomyosarcomas, most frequent first decade of life, and Kaposi sarcoma, a tumor of intermediate malignancy.
Keywords: North Central Nigeria, sarcoma, soft-tissue tumors
How to cite this article:
Vhriterhire RA, Ngbea JA, Akpor IO. Histological spectrum of soft-tissue tumors in a tertiary hospital. Sahel Med J 2020;23:170-8 |
| Introduction | |  |
Soft-tissue tumors are a heterogeneous group of tumors which resemble mesenchymal tissues in the body. They follow different lines of differentiation and may resemble voluntary muscle, adipose tissue, blood vessels, and fibrous tissue. Most of these tumors are benign and have a high cure rate following surgical removal. The soft-tissue sarcomas have an annual incidence of about 5/100,000 per year.[1] Significant efforts have gone into trying to have a comprehensive understanding of these tumors, especially the malignant ones because they pose a considerable diagnostic challenge. Effective therapeutic endeavors for difficult cases often require further interaction between surgeons and pathologists. Even though the management of oncology patients has become targeted or personalized and multidisciplinary approach is now considered optimal, with the use of advanced testing techniques for determining prognosis and guiding therapy,[2] histological section evaluation has remained the gold standard for soft-tissue tumors.[3] However, access to basic histology and immunohistochemistry diagnostic service or more advanced techniques is still fraught with numerous challenges in the resource-challenged regions of Africa.[4] Furthermore, there is still a lack of comprehensive records of histologically diagnosed tumors in the face of the rising incidences of cancers in some parts of Nigeria including the North Central region.[5],[6] This study aimed at developing a comprehensive morphological map of the pattern of soft-tissue tumors histologically diagnosed in our center which will serve as a vital component of our evolving local cancer registry. This work also sought to determine regional variations within the north central and other regions of Nigeria.
| Materials and Methods | | |
This retrospective analysis was performed using the archival records of histologically diagnosed soft-tissue samples submitted in the histopathology laboratory of a tertiary hospital in Makurdi, North Central Nigeria, between January 2014 and December 2017. The duplicate reports and slides were retrieved and analyzed. In some instances, case notes were consulted for demographic and other relevant information not present on the request forms. The tissue blocks of faded or broken slides were also retrieved from the store and resectioned for further evaluation. The specimens used for this study were fixed in formalin and processed routinely. The paraffin wax-embedded tissue blocks were sectioned into 3–5 μ thick sections and stained with hematoxylin and eosin. The slides were evaluated by competent histopathologists. This study was limited by the unavailability of immunohistochemistry or other advanced tools in our center for further evaluation of the tumors beyond the morphology.
This review examined mesenchymal tumors only; thus, skin and osseous tumors and uterine leiomyomas were excluded. The tumors were classified in accordance with the 2013 WHO classification of soft-tissue tumors.[7],[8] The tumors were categorized into adipocytic, fibroblastic, fibrohistiocytic, perivascular, vascular, skeletal muscle, and nerve sheath tumors. Ethical clearance for this research was obtained from the Benue State University Research and Ethics Committee, ref number BSUTH/CMAC/HREC/101/V.I/2020.
The data obtained from this research were handled and analyzed using two statistical software packages, SPSS Statistics, version 23 (IBM Corporation, Armonk, New York, USA) and Microsoft Excel, version 16.0 (Microsoft Corporation, Redmond, Washington, USA). The age, gender, and histological subtype distribution of the soft-tissue tumors, being descriptive data, were presented in tables and a chart.
| Results | | |
One hundred and eighty-eight soft-tissue specimens were evaluated. These accounted for 6% of 3118 tumors diagnosed during the period under review. They comprised 45.7% (86/188) of males and 54.3% (102/188) of females giving 1:1.2 male:female (M: F) ratio. The cases ranged in age from 10 months to 76 years. As represented in [Table 1], our study revealed that soft-tissue tumors were most common in the fourth decade and the overall mean age was 35.05 ± 18.9 years [Table 2] and [Table 3]. | Table 1: Summary of sex and age distribution of benign and malignant soft tissue tumours in Makurdi, North-central Nigeria
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 | Table 3: Grouped distribution and mean age of types of soft tissue tumours
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The benign cases constituted 67.0% (n = 126), with a male: female ratio of 1:1.3 and a mean age of 35.03 ± 18.3 years, and the peak occurrence was in the 30–39 years' age group. The remaining 33.0% (n = 62) were malignant, had a M:F ratio of 1:1, a mean age of 35.1 ± 20.3 years, and peak occurrence a decade later than the benign, that is, in the 40–49 years' age group [Table 2] and [Table 3].
The soft-tissue tumors were broadly categorized, according to histogenesis, into adipocytic, fibroblastic, fibrohistiocytic, perivascular, vascular, skeletal muscle origin, and nerve sheath tumors [Table 2]. [Figure 1] depicts the relative frequencies of the major categories of soft-tissue tumors within the study period on a pie chart. Adipocytic tumors were the most common (n = 60, 31.9%), followed by vascular lesions (n = 53, 28.2%). Perivascular tumors were the least common and accounted for only 1.6% (n = 3). | Figure 1: Frequency of types of soft-tissue tumors in Makurdi, Nigeria, is shown on this pie chart
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Age distribution
The grouped age distribution of the various types of soft-tissue tumors together with their mean age of occurrence is shown in [Table 3]. The mean age of adipocytic tumors was 43.1 ± 15.0 years and their peak occurrence was in the 50–59 years' age group. The mean age of fibrohistiocytic tumors was 49.4 ± 19.1 years, and the peak age of occurrence was at the seventh decade. Fibroblastic tumors had a mean age of 31.1 ± 13.6 years, with a peak occurrence in the fourth decade. The three cases of perivascular tumors found occurred within the 30–39 years' age group and had a mean age of 33.7 ± 3.2 years. The vascular tumors had a mean age of 34.0 ± 19.4 years and had a peak occurrence in the fifth decade. Adipocytic and vascular tumors were the only ones found in the eighth decade and each occurred in equal proportions. The skeletal muscle tumors were most frequent in children in the first decade of life, but the presence of this tumor in the later decades resulted in a largely asymmetric data, a mean age of 25.3 ± 22.3 years, and a moderate positive skewness of 0.61 (Standard error (SE): 0.42) and kurtosis of −1.24 (SE: 0.82). The nerve sheath tumors were found mostly in patients within the third decade and had a mean of 29.0 ± 16.8 years.
Further details on the age distribution of benign and malignant tumors diagnosed during the study period are presented in [Table 4] and [Table 5]. When both categories of diagnoses were considered together, embryonal rhabdomyosarcoma was found in this study to be the most common tumor in the first decade of life. About 62.5% (n = 10/16) of this tumor was found in this age group. It also represented 41.7% (n = 10/24) of all the soft-tissue tumors found in the first decade. In the second decade, embryonal rhabdomyosarcoma and neurofibroma were most frequent, with each representing 17.6% (n = 3/17) of all the soft-tissue tumors in the second decade. Lipoma was the most common soft-tissue tumor in the third, fourth, sixth, and seventh decades. Kaposi sarcoma was most common in the fifth decade. Liposarcoma, cavernous hemangioma, fibrolipoma, and lymphangioma were the tumors found in the eighth decade.
Furthermore, 18.6% (35/188) of the soft-tissue tumors were found in pediatric patients, from 0 to 17 years, inclusive. Fourteen (40%) of the pediatric cases were malignant, representing 22% (n = 14/62) of all the malignant soft-tissue tumors. Alveolar rhabdomyosarcoma and embryonal rhabdomyosarcoma were the two malignant tumors found in these children. Five (31%) of all the 16 embryonal rhabdomyosarcoma cases occurred in children under the age of 5 years, with a subset of two (12.5%) cases in infants. Meanwhile, the remaining 8 cases (50%) were found in children within the 5–17 years' age bracket.
Gender
As shown in [Table 1], 45.7% (n = 86) of all the soft-tissue tumors were found in males, whereas 54.3% (n = 102) occurred in females. Males with benign soft-tissue tumors constituted 29.3% (n = 55/188) of all the soft-tissue tumors and 43.7% (n = 55/126) of the benign subset. Males with malignant lesions constituted 16.5% (n = 31/188) of all cases and 50% (n = 31/62) of the malignant subset. In females, benign cases constituted 37.8% (n = 71/188) of all the tumors and 56.3% (n = 71/126) of all the benign cases. There were an equal number of females and males with malignant soft-tissue tumors. Further details about the sex distribution of benign and malignant soft-tissue tumors are shown in [Table 1].
As shown in [Table 2], the adipocytic tumors were the most common in both genders. The male:female ratio of adipocytic tumors in the study period was 1:1.1, whereas skeletal muscle tumors had a direct reverse of this, that is, a ratio of 1.1:1. Vascular and nerve sheath tumors had a similar M:F ratio of 1:1.3. Fibroblastic, fibrohistiocytic, and perivascular soft-tissue tumors each had an M:F ratio 1:1.8, 1.5:1, and 1:2, respectively [Table 2].
[Table 6] provides details about the sex distribution of the benign and malignant lesions diagnosed during the study period. The most common benign tumor in both males and females was lipoma which accounted for 40% (n = 22) and 38% (n = 27) of the benign tumors in each gender, respectively, and 25.6% of all male tumors and 26.5% of all female tumors, respectively. Similarly, the next most common in both sexes was neurofibroma accounting for 16.4% (n = 9/55) in benign male lesions and 10.5% of all male soft-tissue tumors. Similarly, neurofibroma constituted 14.1% (n = 10/71) of the benign female lesions and 9.8% (n = 10/102) of all the female soft-tissue tumors. The relative gender frequencies of the other tumors are presented in [Table 6]. There were no males with myolipoma, angiofibroma, and glomus tumor. Similarly, there were no females with angiolipoma and nodular fasciitis.
In the malignant category, the study generally showed an equal occurrence of both males and females. Kaposi sarcoma was the most common malignant tumor in males, and this made up 25.8% (n = 8/31) of all the soft-tissue malignant tumors which occurred in males. The next most common malignancy in males was embryonal rhabdomyosarcoma, constituting 22.6% (n = 7/31). This tumor was also the most frequent malignancy in females, constituting 29.0% (n = 9/31) [Table 6].
Histological subtypes
This study found 25 different kinds of diagnostic entities of soft-tissue histogenesis, of which 14 (67.0%) were benign and 11 (30.0%) were malignant disease entities.
Benign conditions
As shown in [Table 6], the most frequent benign condition was lipoma. There were 22 cases of this adipocytic tumor in males which constituted 40% of male benign tumors and 17.5% of all the benign tumors and 11.7% of all soft-tissue tumors. Similarly, there 27 lipoma cases in females observed making up 38% of female benign tumors and 21.4% of benign and 14.4% of all the soft-tissue tumors, respectively. This also represented a male: female ratio of 1:1.2. Thus, lipoma cases made up 38.9% of benign soft-tissue tumors and 26.1% of all soft-tissue tumors. As shown in [Table 4], the frequency of lipoma peaked during the fourth and sixth decades. The remaining benign tumors are presented in [Table 4] and [Table 6] in a ranked other of frequency of occurrence. These included neurofibroma, pyogenic granuloma, cavernous hemangioma, fibroma, capillary hemangioma, fibrolipoma, schwannoma, lymphangioma, myolipoma, angiolipoma, nodular fasciitis, angiofibroma/fibrous papule, and glomus tumor. Further details about the frequency of these benign tumors are shown in Tables 4. The age groups within which these tumors had their highest occurrence frequencies and their sex distribution are depicted in [Table 4] and [Table 6].
Malignant tumors
Eleven different malignant disease entities were diagnosed histologically during the study period spread across both sexes and age groups, ranging from the first to the eighth decade. There were 16 cases of embryonal rhabdomyosarcoma observed in this study, and this tumor was the most frequent malignant tumor and made up to 25.8% (n = 16/62) of the malignant soft-tissue tumors and 8.5% (n = 16/188) of all the soft-tissue tumors seen during this period. There were fewer male, 22.6% (n = 7/16), than female cases, 29.0% (n = 9/16), and this gave a M: F ratio of 1:1.3. Embryonal rhabdomyosarcoma was found most commonly within the first decade of life. The skewness of the data on this tumor has already been presented above.
Tumors of borderline or intermediate malignancy made up 8.5% (n = 16), whereas malignant cases constituted 24.5% (n = 46) of all the soft-tissue tumors. Kaposi sarcoma and hemangioendothelioma were the two tumors of intermediate or borderline malignancy found in this study. The frequency of Kaposi sarcoma closely followed that of embryonal rhabdomyosarcoma accounting for 24.2% (n = 15/62) of the malignant soft-tissue tumors and 8.0% (n = 15/188) of all the soft-tissue tumors. It was slightly more common in males than females [Table 6]. The remaining malignant soft-tissue tumors found in this study included pleomorphic rhabdomyosarcoma, alveolar rhabdomyosarcoma, liposarcoma, angiosarcoma, pleomorphic sarcoma, malignant fibrous histiocytoma, and hemangiopericytoma. These are shown in [Table 5] and [Table 6], with tumors ranked in the order of frequency of occurrence.
| Discussion | | |
Tumors of mesenchymal cell origin occur across a wide age range and in both sexes. The present of these tumors between 1-month and 76-year-old patients in our study is congruent with findings by other researchers who have also reported broad age ranges.[9] Our study found that benign soft-tissue tumors were histologically diagnosed twice as much as malignant ones during the period of review. Moderately higher proportions were observed in India by Harpal et al. in a series of 200 soft-tissue biopsies with 84.5% (n = 169/200) benign, 10% (n = 20/200) malignant, and 5.5% (n = 11/200) classified as tumors of intermediate malignancy.[9] Even much high proportions of 91% benign and 9% malignant in a series of 111 soft-tissue tumors were also reported in India.[10]
Soft-tissue tumors were more common in females than males in our study. Similar to our finding of 1:1.2 male: female ratio, Mohammed et al. and Ikeri et al. reported 1:1.1 and 1:1.3 from Zaria and Lagos, respectively.[11],[12] An analysis of 264 soft-tissue cases in Kano gave a ratio of 1.6:1 unlike the preponderance of females in our study.[13] There were also more cases of males with soft-tissue sarcoma reported from Sokoto (male: female ratio, 1.9:1).[14] Similarly, a ratio of 2.1:1 was reported in India by Sundar.[15] This preponderance of soft-tissue tumors in females in our study was accounted for by the higher frequency of lipoma among females. In our review, lipoma accounted for 26.1% (n = 49/188) of all the soft-tissue tumors, of which 45% (n = 27/49) occurred in females. The findings from other places in Nigeria have not been too different. In Zaria, for instance, lipoma accounted for 42.6% (n = 172/403) of females with adipocytic tumors, as reported by Mohammed et al.[11] Odokuma et al. evaluated a series of 325 adipocytic tumors in Benin, Mid-Western Nigeria, and found that 49.8% of them were females.[16] In contrast, lipoma made up 81.7% (n = 49/60) of all adipocytic tumors in our study, also similar to the 81.4% (n = 328/403) reported in Zaria, giving a rather striking similarity in the findings from both places.[11]
Liposarcoma was the only malignant adipocytic tumor in our study and constituted only 2.1% (4/188) all soft-tissue tumors and 6.7% (4/61) of all the malignant variants. In Benin, liposarcoma constituted 4% (13/325) of adipocytic tumors, <6.7% in our study. Yusuf et al. reported that 12.1% (32/264) of soft-tissue sarcomas were liposarcomas in Kano, a figure almost twice the 6.7% obtained in our study. In comparison with our study, 5.6% (6/108) and 5.7% (n = 7/123) were found in Jos and Sokoto, respectively.[14],[17]
The vascular tumors found in this review included hemangioma, Kaposi sarcoma, hemangioendothelioma, and angiosarcoma, all of which formed over a quarter of all the soft-tissue tumors, with Kaposi sarcoma being the most common. Histologically, the tumor is characterized by proliferation of spindle cells and irregular vascular spaces and runs a gamut from the patch and plaque to the nodular phases.[18] It formed 8% (n = 15/188) of all the soft-tissue tumors and 28.3% (n = 15/53) of the vascular tumors in this review. In Benin, Obaseki et al. initially reported that Kaposi sarcoma composed 13.6% (n = 22/162) of vascular tumors, but the trend changed over time following a later report, by Forae and Obaseki, of 29.4% (79/269) 5 years later, a figure closer to the 28.3% (n = 15/53) we observed in Makurdi.[19],[20] A slightly higher figure of 30.8% (16/52) was reported from Lagos in a recent paper[12] and a lower one, 21.6% (66/305), was obtained in Kano.[13] Another review of 182 cases of Kaposi sarcoma in Lagos showed that this tumor constituted 1.2% of patients managed for HIV/AIDS and 2.9% of solid malignant tumors.[21]
In this review, the tumors of skeletal muscle histogenesis were all malignant and collectively constituted the most common of the malignant neoplasms [Table 6]. Observation of reports from other parts of the country seems to show significant similarities. For instance, Aliyu et al. reported 39% (48/123) in Sokoto, whereas we found that 50.8% (n = 31/61) of malignant soft-tissue tumors were rhabdomyosarcomas.[14] This was the most common soft-tissue sarcoma found in children. Our study observed that embryonal rhabdomyosarcoma was the most common variant and it formed 51.5% of all the rhabdomyosarcomas present and 92.9% of the malignant tumors present in children from 0 to 17 years. The leading incidence of this childhood tumor was also previously reported from Jos, where rhabdomyosarcoma formed 31.0% of 87 malignant childhood tumors evaluated.[22] This report, however, differed from our own in that it included other types of malignancies also found in children such as osteosarcoma, lymphoma, and retinoblastoma.[22] Similar to our findings, an analysis at Ibadan noted a preponderance of embryonal rhabdomyosarcoma which formed 61.5% of 91 rhabdomyosarcoma cases.[23] This tumor was also described to be the most frequent (39.4%) of 66 soft-tissue sarcomas evaluated in Port Harcourt.[24] Reports from Southeastern Nigeria[25],[26] and Uyo[27] suggest a less frequent occurrence in that region. Rhabdomyosarcoma composed of 5.5% of 309 childhood malignancies in a report in Ghana.[28] A low proportion of 1.8% was also reported from India in a series of 111 soft-tissue tumors.[10]
On the other hand, the nerve sheath tumors were mostly benign and composed mainly of neurofibroma. Histologically, this tumor, composed of irregular neural fascicles, exhibits Schwann cells with serpentine or curved dark nuclei, fibroblasts, strands of collagen, and mast cells disposed in a myxoid stroma.[29] It is a component of von Recklinghausen's syndrome (Type 1 neurofibromatosis) but can also occur as a solitary tumor, mainly in the head-and-neck region. Although thought to be uncommon in Nigeria, a report from Maiduguri[30] suggests that Type 1 neurofibromatosis may not be as rare as assumed. Most of the cases in that report occurred as solitary forms. Similarly, in this our study, all the cases were solitary and constituted just over 10% of all the soft-tissue tumors. Similarly, neurofibroma composed 24.4% of a series of 188 benign cutaneous tumors in a recent study in Benin.[31]
The diagnosis of soft-tissue tumors sometimes poses peculiar challenges to surgeons and pathologists. A diagnostic discrepancy study on 1703 surgical pathology specimens by Vhriterhire et al. disclosed that differences between clinical diagnosis made by surgeons and histopathology laboratory diagnosis were most likely to occur in tumors of soft-tissue origin when compared with epithelial or lymphoid lesions from other organs and tissues.[32] Thway and Fisher, in a similar study in a specialized sarcoma center, strongly advocated the employment of advanced ancillary studies in the diagnosis of soft-tissue tumors.[33] In line with this thought, molecular genetics is increasingly being used to support diagnosis in noncanonical presentations or histological appearances.[1] Employment of immunohistochemistry service in many histopathology laboratories in Nigeria for the diagnosis of tumors is still fraught with key stumbling blocks that limit its use.[34] The situation in our center is similar to what obtains in other centers where pathologists employ clinical experience, knowledge, and skill of interpreting morphology to arrive at diagnoses.[35] This work is thus limited by the absence of immunohistochemistry for confirmation of the tumors with potentials for diagnostic dilemma. In respect of these challenges in Nigeria, we do advocate for the adoption of a model similar to the one reported by Patel et al. which was used for the rapid development and validation of immunohistochemistry laboratory service in Kenya.[4]
| Conclusion | | |
This study examined the incidence of histologically diagnosed soft-tissue tumors in North Central Nigeria. The benign soft-tissue tumors were mostly lipoma found more in female patients. Half of all the malignant tumors consisted of embryonal rhabdomyosarcomas which occurred mostly in the first decade of life and Kaposi sarcoma, a tumor of intermediate malignancy.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]
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