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ORIGINAL ARTICLE |
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Year : 2016 | Volume
: 19
| Issue : 2 | Page : 74-81 |
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A 20 year retrospective histomorphological analysis of juvenile soft tissue tumors
Odokuma Emmanuel Igho
Department of Human Anatomy and Cell Biology, Delta State University, Abraka, Delta State, Nigeria
Date of Web Publication | 12-Jul-2016 |
Correspondence Address: Odokuma Emmanuel Igho Department of Human Anatomy and Cell Biology, Delta State University, Abraka, Delta State Nigeria
Source of Support: None, Conflict of Interest: None | Check |
DOI: 10.4103/1118-8561.186032
Introduction: Soft tissue tumours (STT) are defined traditionally as mesenchymal proliferations that occur in the extra-.skeletal nonepithelial tissues of the body excluding viscera, meninges and lymphoreticular system. These tumours occur in children where they may result in severe debilitating disease. This study was therefore aimed at determining the age, gender and site distribution of soft tissue tumours in the young. Materials and Methods: The records of all pathology consultations during the 20 year period from (1990-2010), from the Department of Morbid Anatomy/Histopathology, University of Benin Teaching Hospital from birth to 20 years, were utilized for this study. The lesions were standardized in accordance with the world health organization (WHO) classification. Permission for this study was obtained from the UBTH ethics committee (protocol number ADM/E22/A/VOL.VII/142). Results: A total of 139 lesions were recorded, 72 males and 67 females with a male/female ratio of 1.1:1. Benign tumours constituted 113(81%) while malignant tumours accounted for 26(19%). This study demonstrated that, nerve sheath tumours and vascular tumours accounted for 25% of STT in children followed by adipocytic tumours 22%, skeletal muscle tumours 17%, fibrohistiocytic tumours 7%, fibroblastic tumours 5%, and perivascular tumours 1% respectively. Majority of these tumours were located in the head and lower extremities with fewer in the upper extremities and trunk. These lesions were predominant in females of the older age group (10-20 years) unlike in their male counterparts. Conclusion: This study has shown that benign soft tissue tumours are more prevalent than the malignant varieties in juveniles. Keywords: Benign, juvenile, patterns, sarcoma
How to cite this article: Igho OE. A 20 year retrospective histomorphological analysis of juvenile soft tissue tumors. Sahel Med J 2016;19:74-81 |
Introduction | | |
Soft tissue tumors (STT) are defined traditionally as mesenchymal proliferations that occur in the extra-skeletal nonepithelial tissues of the body excluding viscera, meninges, and lymphoreticular system.[1] These tumors have been demonstrated in children where they may result in severe debilitating disease.[1]
In an earlier report on STT, Coffin and Dehner demonstrated that majority of the cases were benign with borderline and malignant cases accounting for the remaining few.[2] They also showed that benign lesions were more likely to occur in children than adults with the head and neck regions constituting the vast majority.
Childhood STT are classified like their counterpart adult lesions and may be benign or malignant (sarcomas).[3] Generally, the etiology of most STT are unknown, but they have however been associated with irradiation, chemicals, and heat burns as well as trauma in addition to viruses, genetic causes, and immunosuppression.[4] Though benign STT have been demonstrated to be more common than their malignant counterparts, recent literature on STT from Nigeria have emphasized adult sarcomas with scant reference to benign STT, which are known to be associated with less fatality but are usually associated with a huge financial burden from attempts at cosmetic surgery.[2] This study was therefore aimed at determining the patterns of STT in the young.
Materials and Methods | | |
This was a 20-year retrospective study involving records of patients seen in consultation by the Department of Morbid Anatomy, University of Benin Teaching Hospital (UBTH) during the 20 years period commencing from 1990 and ending 2010 retrospectively. Clinical information including age, sex, and site of lesions were obtained from the available surgical pathology records. A total of 139 patients were recorded over the 20 years period of review. All tissue samples analyzed in the pathology unit were included, both of in-patients and those of out-patients. Cases, where tissue blocks could not be found, were excluded from this study. Tissue blocks were analyzed using standard techniques. The lesions were individually reviewed and standardized in accordance with the classification system of the World Health Organization.[5],[6] Data obtained were coded and entered into Microsoft excel spreadsheet, and the types, age, gender, and sites were presented in tables, charts, and micrographs. Approval for this study was obtained from the UBTH Ethics Committee (protocol number ADM/E22/A/VOL.VII/142). Declaration of Helsinki in 1995(revised in Edinburgh 2000).[7]
Results | | |
A total of 139 lesions were recorded, 72 males and 67 females with a male:female ratio of 1.1:1. Benign tumors constituted the bulk (81%) of the childhood STT whereas the remaining were malignant (19%).
This study showed that adipocytic tumors accounted for 30 (22%) of STT in children and lipomas were the most predominant adipocytic tumor subtype constituting 25 (83%) of adipocytic lesions [Table 1]. The other subtypes included lipoblastoma 1 (3.3%), myolipoma 1 (3.3%), hibernoma 1 (3.3%), and the malignant variant, liposarcoma 2 (7%). These tumors showed a generalized body distribution with the lower extremities having the highest contribution, (30%). This was followed by the head (23.3%), upper extremities (20%), trunk (13.3%), and neck (3.3%). The other sites included the skin and groin. Males in the first 10 years of life were observed to have more of these tumors than females in whom the tumors predominated between 10 and 20 years. The male/female ratio was 1.3:1 [Table 1] and as shown in [Figure 1]a, lipoma, a benign lesion, was composed of mature adipocytes with peripherally disposed nuclei, arranged in lobules by fibroconnective tissue stroma. Similarly, [Figure 1]b, lipoblastoma, showed mature and immature adipocytes of variable sizes separated by a thin connective tissue stroma. The nuclei were bland but prominent. | Table 1: Type gender and age distribution of soft tissue tumors (20 years and below)
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| Figure 1: (a) Lipoma (H and E, ×400). (b) Lipoblastoma (H and E, ×100). (c) Fibroma (H and E, ×100). (d) Benign fibrous histiocytomas (H and E, ×100). (e) Benign fibrous histiocytomas (H and E, ×400). (f) Giant cell tumor (H and E, ×100). (g) Giant cell tumor (H and E, ×400). (h) Malignant fibrous histioctytoma (H and E, ×100). (i) Malignant fibrous histioctytoma (H and E, ×400). (j) Alveolar rhabdomyosarcoma (H and E, ×100). (k) Alveolar rhabdomyosarcoma (H and E, ×400). (l) Hemangioma (H and E, ×100). (m) Kaposi sarcoma (H and E, ×100). (n) Neurofibroma (H and E, ×100). (o) Granular cell tumor (H and E, ×40). (p) Granular cell tumor (H and E, ×100). (q) Malignant peripheral nerve sheath tumor (H and E, ×40). (r) Malignant peripheral nerve sheath tumor (H and E, ×100)
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Fibroblastic tumors accounted for 7 (5%) of STT with fibroma constituting majority of the subtype in 6 (86%) of fibroblastic lesions, whereas 1 (14%) of the lesions were nodular fasciitis [Table 1]. These tumors were mainly distributed in the lower extremities, followed by the upper extremities and head (14% each) [Table 2]. Males in the first decade of life were mainly affected than females (25%), whereas females predominated in the second decade [Table 2]. The fibroma shown in [Figure 1]c was composed of nodules separated by narrow clefts. The nodules were paucicellular and contained spindle fibroblast embedded in a collagenous stroma. Few slit-like spaces were seen. A segment of the capsule was also demonstrated.
Fibrohistiocytic tumors were the fifth most common STT type, observed constituting 10 (7%) of soft tissue lesions in the index study. The subtypes described were benign giant cell tumor of tendon sheath which accounted for 5 (4%) of benign fibrohistiocytoma (BFH) 4 (4%), whereas malignant BFH (MFH) comprised 1 (1%) of soft tissues tumors in children as shown in in [Figure 1]f and [Figure 1]g [Table 1]. The upper extremities, lower extremities, and head were the common sites of distribution in most of the described cases [Table 2]. Females both in the first and second decades of life had most of these lesions with a female:male ratio of 1.5:1. As shown in [Figure 1]d and [Figure 1]e, benign fibrous histiocytomas were observed to display foci of prominent storiform patterns with few histiocytes, histiocytic giant cells, and fibroblasts in a background of collagen. In [Figure 1]h and [Figure 1]i, malignant fibrous histioctytoma showed sheets of xanthoma cells with a mixed inflammatory cell infiltrate disposed in a collagenous background. A giant cell was seen in the center of the lesion.{Table 1}
Perivascular tumors accounted the least STT in children and constituting 1 (1%) of soft tissue lesions with hemangiopericytoma as the only subtype observed [Table 1]. The head was the only site of occurrence, and it was observed in a male in the first decade [Table 1] and [Table 2].
Skeletal muscle tumors comprised 23 (17%) of the entire lesions and were the fourth most common STT in the index study. The subtypes observed were rhabdomyoma which is benign 4 (17%), whereas the malignant variants were embryonal rhabdomyosarcoma 8 (35%), alveolar rhabdomyosarcoma 3 (13%), and pleomorphic rhabdomyosarcoma 8 (35%) [Table 1]. Their major location of occurrence was the head (52%), trunk (4%), and trunk and lower extremities (9%) [Table 2]. The study showed that males both in the first and second decades of life had more of these lesions (male:female ratio: 2:1). In [Figure 1]j and [Figure 1]k, the displayed alveolar rhabdomyosarcoma showed a malignant neoplastic lesion composed of rhabdomyoblast at different stages of development disposed in clusters surrounding cyst-like spaces. Individual cells showed marked hyperchromasia.
Vascular tumors comprised 34 (25%) cases of STT in this study. Capillary hemangioma was its most frequent subtype constituting 16 (47%) of vascular tumors and 12% of STT respectfully followed by cavernous hemangioma 8 (24%), lymphangioma 3 (12%), pyogenic granuloma 4 (9%), and Kaposi sarcoma (KS) 3 (9%) as shown in [Table 1]. The upper extremities, head, and lower extremities were the most common sites of occurrence accounting for (32%), (26%), and (24%) of site of occurrence of vascular soft tumors, respectively, whereas the neck comprised only (6%) as shown in [Table 2]. Females of both the first and second decade predominated with a female:male ratio of 1.6:1 [Table 1]. As shown in [Figure 1]l, hemangioma was observed to demonstrate several variously sized blood vessels with thin walls and lumen filled with blood. The vessels were disposed in loose connective tissue stroma in which lymphoplasmacytic cell infiltrates. In [Figure 1]m, KS showed several thin-walled vascular spaces lined by atypical spindle cells. The nuclei of these cells were round to oval, and there was marked extravasation of red blood cells into the intervening loose connective tissue stroma.
Nerve sheath tumors (NSTs) also accounted for 34 (25%) of STT in studied as shown in [Table 1]. Neurofibroma was the most frequent subtype in this category accounting for 27 (79%) of nerve sheath lesions, whereas schwannoma constituted 3 (9%), granular cell tumors 2 (6%), benign peripheral NST 1 (3%), and the malignant variant malignant peripheral NST 1 (3%). These lesions were disposed mainly in the head (35%), lower extremities (29% each), and upper extremities (21%). There was an observed female predominance of lesions in the first decade, whereas the second decade showed male preponderance. Generally, however, the male:female ratio was 1:1. In [Figure 1]n, several spindle cells disposed in bundles with areas of mild palisading are shown. The nerve bundles were interspersed by fibroconnective tissue stroma (neurofibroma). There were infiltrating sheaths or cords of polygonal bland cells with well-defined cell borders, abundant eosinophilic granular cytoplasm and round to oval nuclei with prominent nucleoli as shown in [Figure 1]o and [Figure 1]p. The intervening stroma was collagenous (granular cell tumor). In [Figure 1]q and [Figure 1]r, several bland fibroblast-like cells disposed in a myxoid background with few associated inflammatory cells seen. These features were in keeping with malignant peripheral NST.
Discussion | | |
This study has showed that over the 20 years period (1990–2010), a 139 cases of STT were reported in the Histopathology Department of UBTH, Benin City. Benign STT were more prevalent than the malignant variety.
In the index study, lipoma's, a benign adipocytic tumor, constituted the majority of the lesions in this group. Similar reports have been observed in India and Rwanda where lipoma accounted for 20.5% and 23.5% in children.[1],[8] This index study showed an equal gender distribution which was not different from previous findings [9],[10] though females in the second decade of life were shown to account for the majority of the lesions. Several factors including genetic predisposition, exposure to hazardous chemical agents and radiation have been suggested to contribute to these changes.[11] The other benign adipocytic tumors, lipoblastoma, myolipoma, and hibernoma, were rare as had been shown in earlier reports.[12],[13],[14],[15],[16]
Liposarcomas have been reported to be rare in pediatric age.[17],[18],[19] In the index study, it accounted for few malignant STT among the studied population. The findings were higher when compared with studies in the United States, where it was observed that it comprised<3% of soft tissue sarcomas in children and was usually in the second decade. The site of occurrence in the USA study was the lower extremities in 51% of cases with male:female ratio of 1:1.9[18] as shown in the index study.
The current study demonstrated that fibroblastic tumors formed the major benign STT involving only nodular fasciitis and fibroma which were both observed to constitute a minor percentage of STT in children. In a study series by Coffin et al., it was reported that fibroblastic tumors accounted for about 12% of pediatric soft tissue tumors and that benign fibroblastic tumors were the most predominant fibroblastic STT accounting for 76% of cases.[20] These findings far exceeded the observation in this study and could be explained by the large population analyzed unlike in the index study. The male:female ratio was also slightly fewer than was observed by Coffin and Dehner, who demonstrated a male:female ratio of 1.8:1, but showed a similar site and age distribution.[2],[20]
The fibrohistiocytic tumors recorded in this study were BFH and benign giant cell tumor of tendon sheath. BFH displayed a male predilection particularly within the second decade and predominantly in the extremities. A similar study in the USA demonstrated that about a third of these tumors were peculiar to the upper and lower extremities, respectively.[21] In contrast, some other authors in America, Italy, Saudi, reported that the head, neck, and trunk (breast) regions were the most common sites of this lesion. Another report demonstrated that the age predilection was also within the first 20 years as was outlined in the index study with a higher male involvement.[22],[23],[24],[25] The sex predilection for benign giant cell tumor of tendon sheath differed from previous reports were it was observed that females in the first decade predominated over their male counterparts.[26],[27],[28] The reason for the observed gender dominance is unknown.[27]
MFH accounted for a minor percentage of soft tissue malignancies observed during the period of study. Available literature had reported that this lesion occurred within the first and second decade of life with the common sites of occurrence being the head, neck, and extremities.[29] This was contrary to the findings in the index study which recorded a higher percentage, especially occurring in the second decade and only observed in a female. The recorded percentage in the current study was much higher than was documented by Daw et al. among nonrhabdomyosarcomas in pediatric tumors.[30] Generally, the gender predominance of fibrohistiocytic tumors were in conformity with reviews by Eemstein and Enzinger who demonstrated a male:female ratio of 1:2.4 and 1:6, respectively, and upper extremities predominance in 63.1% and 64% of cases, respectively.[30],[31],[32]
Hemangiopericytoma has been described as an extremely rare perivascular tumor with little data available on its clinical course and management.[33] A single lesion was observed in this group in the studied population accounting for the least of the STT as was observed in a 10 years review in Benin City, Nigeria, where hemangiopericytoma accounted only 1% of vascular tumors recorded.[34] There was a male predilection in the index study which was similar to a report elsewhere.[32] However, a study among polish children reported a female predominance.[35] The site of occurrence differed from that reported by Bien et al.,[33] where the lower extremities and trunk were described as the most common sites for this lesion.[32]
Rhabdomyomas were the only benign skeletal muscle tumors observed in the index study. The index study showed a male predilection both in the first and second decade of life in keeping with reports where fetal rhabdomyomas were outlined to mainly affect males between birth and 3 years of age [36] especially the head and neck regions.[36]
Rhabdomyosarcomas, on the other hand, accounted for the most common malignant STT in the studied population as was recorded elsewhere in children.[29],[36],[37],[38],[39],[40] The head and neck was the most common location for these tumors in the index study and was similar to other studies [29],[30],[40] but was in contrast with some other studies,[37],[39],[41] where the extremities were stated to be their most frequent sites. Among the subtypes of rhabdomyosarcomas, embryonal rhabdomyosarcoma was the most predominant followed by alveolar rhabdomyosarcoma and pleomorphic rhabdomyosarcoma. Although pleomorphic rhabdomyosarcomas have been shown to be more prevalent in adults,[42] in the studied population, it demonstrated an equal percentage with the embryonal subtype. A study in Tunisia had earlier reported that rhabdomyosarcomas represented over half of the soft tissue sarcomas.[43] This observation was, however, higher than was expressed in the index study. The Tunisian study also revealed a male: female ratio of 2.7:1 which was higher than demonstrated in this study.[43] Similarly, a much higher male: female ratio of 3.2:1 was observed in Port Harcourt, Nigeria, were embryonal subtype was observed to be the most predominant than was recorded in this study. The age and site predilection were, however, comparable to those in Tunisia and Nigeria.[43],[44]
This tumor accounted for the second most predominant STT recorded in the entire study. The incidence of these tumors were similar to observations elsewhere, where vascular tumors accounted for about a quarter of STT.[34],[44] The male:female ratio of vascular tumors in the index study was higher than that observed in Benin City, Nigeria.[34]
This study showed that hemangiomas were the most abundant of the vascular tumors with capillary hemangioma being the most predominant subtype followed by cavernous hemangioma, lymphangioma, pyogenic granuloma, and KS. A similar observation was made by Coffin et al., and Obaseki et al., in Benin City where hemangiomas were described as the most common benign STT of infancy and childhood.[34],[45] The sex and age predilection was in conformity with the report by Coffin et al. (1:2) but different from that of Obaseki et al. in Benin City, where an equal distribution of vascular tumors among sex and age was recorded.[34],[45] The sites of occurrence of these tumors were in common with other studies, but with the head and neck regions being most common in (60%) of cases, followed by the trunk (25%) and the extremities (15%).[46],[47] A similar report demonstrated that the head and neck, extremities, and trunk were more common sites of distribution than elsewhere.[45]
KS was the only malignant vascular lesion observed in the index study. The percentage of KS in the index study was fewer than was recorded for vascular tumors in Kano and Jos, Nigeria, where the tumor was observed to accounted for 16% and 26% of vascular tumors.[41],[48] The values in the index study were, however, higher than findings in Benin City where KS constituted the only malignant vascular tumor comprising 6% of cases.[34] The site predilection of this tumor in the index study was identical with that in Jos [41] but different from the Kano report where the head and neck was demonstrated to be the most common site of affectation.[48]
NSTs constituted the most abundant STT alongside with vascular tumors in the index study. Neurofibroma was the most common NST, and also, the most predominant STT in the studied population. Neurofibromas have been reported to be one of the most predominant STT in children.[49] A review in the USA showed that benign nerve tumors predominated (60%) unlike in the index study where benign tumors constituted 97% of cases.[50] The sites of occurrence of these tumors in the current study differed with that reported by Coffin et al., where the trunk was described as the major site of these tumors in 48% of cases followed by the head and neck 29%, and extremities 23%.[50]
Conclusion | | |
This study also demonstrated that benign STT were more predominant than their malignant counterparts within the studied age group. STT recorded during this 20 years retrospective study revealed that NSTs, vascular tumors and adipocytic tumors were the most common tumors in this category.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References | | |
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[Figure 1]
[Table 1], [Table 2]
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