| Abstract|| |
Background: Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. Anaplasia is a rare phenomenon seen in childhood RMS. The most common histologic subtype was Embryonal followed by Alveolar and spindle subtype. Design: A total of 11 cases of pediatric RMS were selected from January 2017 to June 2019 presenting at various sites. Out of 11 cases, 2 were further diagnosed as Embryonal, 2 as Alveolar, 2 as Pleomorphic, 1 as Spindle subtype and rest 4 as RMS-NOS based on morphology. All cases were positive for Desmin. The presence of cells with lobated, hyperchromatic nuclei at least three times larger than the tumor cell (anaplastic cells) was selected as the main criterion to diagnose Anaplasia. Results: Out of the total 11 cases, anaplasia was seen in 7 cases. Out of these seven, five cases showed Focal Anaplasia (FA) (71.4%) and 2 cases showed Diffuse Anaplasia (DA) (28.6%). Out of 2 cases of Embryonal RMS one exhibited focal anaplasia (50%). One case of Spindle RMS showed diffuse anaplasia, 2 cases of pleomorphic RMS showed focal anaplasia. Out of 3 cases of RMS- NOS, 2 exhibited focal anaplaisa and one displayed Diffuse anaplasia. Both Alveolar RMS had no features of anaplasia. Conclusion: Presence of Anaplasia is a frequent observation in pediatric RMS. Anaplasia is often under reported in pediatric RMS. Pathologist should be more aware of this rare phenomenon.
Keywords: Anaplasia, pediatric, rhabdomyosarcoma
|How to cite this article:|
Ahuja M, Tomar R, Thakur S, Mallya V, Mandal S, Khurana N, Sarin Y K. Anaplasia in childhood rhabdomyosarcoma: An under reported entity. Indian J Pathol Microbiol 2022;65:864-8
|How to cite this URL:|
Ahuja M, Tomar R, Thakur S, Mallya V, Mandal S, Khurana N, Sarin Y K. Anaplasia in childhood rhabdomyosarcoma: An under reported entity. Indian J Pathol Microbiol [serial online] 2022 [cited 2022 Dec 7];65:864-8. Available from: https://www.ijpmonline.org/text.asp?2022/65/4/864/359313
| Introduction|| |
Rhabdomyosarcoma is not only the most common soft tissue sarcoma in children under 15 years of the age, but also one of the most common soft tissue sarcomas in adolescents and young adults. It is estimated that RMS accounts for about 8% of cancer in children with an annual incidence of 6.4 million cases per million neonates and infants each year and 4.5 million cases per million children and adolescents per year.
International society for pediatric oncology classifies rhabdomyosarcoma into following types: 1) Embryonal sarcoma 2) Embryonal RMS- loose a) botyroid b) non botyroid and dense a) well differentiated b) poorly differentiated, 3) Alveolar RMS, Adult pleomorphic RMS, Other specified soft tissue sarcoma and Sarcoma, not otherwise specified.
According to the prognosis, the IRS group classified tumors and proposed a scheme called International classification of Rhabdomyosarcoma. According to this, the tumor is classified into: Superior prognosis- 1) Botryoid rhabdomyosarcoma 2) Spindle cell rhabdomyosarcoma. Intermediate prognosis -Embryonal rhabdomyosarcoma. Poor prognosis- 1) Alveolar rhabdomyosarcoma 2) Undifferentiated sarcoma. Subtypes whose prognosis is not presently evaluable - Rhabdomyosarcoma with rhabdoid features.
Despite the striking diversity in location, RMS has a fairly uniform age distribution. It occurs predominantly in infants and children and less commonly in adolescents and young adults. Each of the subtypes of RMS has a characteristic age group. For example: embryonal RMS, botyroid type and spindle cell type are more commonly seen in children between birth and 15 years of age and alveolar RMS mainly affects the older patients with peak age of 10-25 years. Embryonal RMS (eRMS), the most common subtype, usually occurs before 10 years of age. Chemotherapy, surgery, and/or radiation comprise standard therapy for patients with RMS. Rhabdomyosarcomas are uncommon in patients older than 40 years. RMS in adults are often pleomorphic type with median age range of 50-56 years. and is rarely seen in children. In children, the term anaplasia is preferred. Males are affected more commonly than females by the ratio of 1.3:1.
Although RMS can arise anywhere in the body, they are more commonly seen in three regions: the head and neck, genitourinary and retroperitoneum and upper & lower extremities.
Grossly the tumors growing on the body cavities like nasopharynx and urinary bladder, are generally well circumscribed, multinodular or polyploid. On cross section, they appear glistening, gelatinous, gray white with patchy areas of hemorrhage and cystic change. The deep seated tumors arising from the musculature are less well defined and almost always infiltrate the surrounding tissues. They are more firm, rubbery and have gray white to pink tan, smooth or finely granular surface. They are often associated with necrosis and cystic degeneration.
Anaplasia is rare in childhood RMS and is not included in the international classification of RMS.The degree of anaplasia was further defined not just by relative quantity but also apparent clonal expansion of the anaplastic nuclei in the tumor. Type I tumors as defined by Kodet included anaplastic cells loosely scattered among non-anaplastic cells (so called focal anaplasia), and type II tumors included those with anaplastic cells that were aggregated in clusters or formed continuous sheets. Despite the suggestion that anaplasia could significantly affect outcome, its relative rarity and lack of reproducibility on multi-reviewer studies precluded incorporation of this feature as a morphologic criteria for assessment in the International Classification of Rhabdomyosarcoma.
In humans, genetic susceptibility to develop RMS has been linked to germline mutations in PTCH1, HRAS, NF1, DICER1, and TP53. It has been seen in conjunction with syndromes like Familial Polyposis Coli, Costello syndrome, Type 1 Neurofibromatosis, Noonan syndrome, Beckwith Wiedemann syndrome and also with Congenital Retinoblastoma.
The aim of this study was to study the incidence of anaplasia in childhood RMS and also emphasize on its inclusion in the pathology report as it can affect the clinical outcome of the patient.
| Material and Methods|| |
A retrospective study was conducted in the department of pathology, Maulana Azad Medical college from a period of July 2017 to December 2019. All the cases of pediatric age group with newly diagnosed RMS registered at the college were included in the study [Figure 1]. Their ages ranged from 1 year to 15 years. The study included total of 11 cases out of which 3 were males and 8 were females.
|Figure 1: (a) Embryonal rhabdomyosarcoma 200×, (b) Spindle rhabdomyosarcoma 200×, (c) Alveolar rhabdomyosarcoma 200×, (d) RMS- NOS 200x|
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All the cases were reviewed by two pathologists for the presence of anaplasia. The cases were segregated on the basis of age, gender and classified according to their morphology and International classification of Childhood Sarcomas.
The immunohistochemistry technique is used for identification of tissue antigens and help in differentiating the tumor. The procedure is done by antigen retrieval from the tissue block followed by non-specific site block, endogenous peroxidase block, primary antibody incubation, secondary antibody incubation, chromogen substrate (DAB), revealing and counterstaining and also slide mounting and storage. Immunohistochemical markers like Desmin (Source: Pathsitu USA), Myogenin and Myo D1 (Source: Scytek Lab USA), SMA (Source: Pathsitu USA), and Vimentin (Source: Thermoscientific USA), were applied in the current study for the confirmation of diagnosis. All antibodies were Ready to use (RTU) The markers that turned out to be positive were Desmin, SMA and Vimentin [Figure 2].
|Figure 2: (a) Desmin cytoplasmic positivity 200×, (b) Myogenin cytoplasmic positivity 200×, (c) Myo D1 nuclear positivity 200×|
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Anaplasia was defined as the presence of abnormal mitotic figures with marked nuclear enlargement and hyperchromasia (at least 3 times the size of neighboring nuclei). Anaplastic cells present in few localized areas dispersed within the primary tumor were labelled as Focal Anaplasia, while those present in groups or continuous sheets were classified as Diffuse Anaplasia [Figure 3] and [Figure 4].
|Figure 3: (a) Focal Anaplasia 200×, (b) Focal anaplasia with apoptotic bodies (arrow) 200×|
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|Figure 4: (a) Diffuse Anaplasia 400×, (b) Diffuse Anaplasia with mitosis (arrow) 200×|
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The presence or absence of anaplasia (diffuse or focal) was correlated with clinical and pathological variables including age, sex, primary tumor site, histologic subtype.
| Results|| |
The study included 11 newly diagnosed cases of RMS recruited from July 1017 to December 2019.
Out to the total 11, 7 cases were < 5 years of age and 4 cases were > 5 years. The median age of diagnosis was 3 years. Patients presented with age group between 1- 15 years, 4 cases being 1 year old, one was 2 years old, one was 3 years, another one 4 years, 2 cases 6 years, one 7 years and one 15 years old.
The male to female ratio was 0.4:1.
Out of the total cases, 4 cases were found in Lower Extremities (2 Pleomorphic, 1 alveolar RMS and Embryonal RMS), 1 case was found in Upper Extremity (RMS-NOS), 2 cases in Head and Neck area (1 Spindle RMS and 1 Alveolar RMS), 3 cases in Abdominal area (all 3 RMS-NOS) and 1 case in Bladder [Table 1].
Out of the total 11 cases, 2 patients were diagnosed with embryonal tumors and 2 cases had pleomorphic subtype, 2 alveolar RMS, 1 spindle cell RMS and 4 cases of RMS- NOS. Anaplasia was identified in 7 patients (out of 11) (63.33%). Of these patients, 5 cases showed focal anaplasia (45.45%) and 2 cases had diffuse anaplasia (18.18%) [Table 2].
Focal anaplasia was reported in one case of Embryonal RMS, 2 cases of Pleomorphic RMS and 2 cases of RMS- NOS. Diffuse anaplasia was reported in one case of Spindle cell RMS and one case of RMS-NOS. Immunohistochemistry findings in Anaplasia could not be well observed.
| Discussion|| |
In this study we documented the prevalence of RMS in childhood and it is more common in children from 1-6 years (mean age being 3 years). RMS is found more in females. Also anaplasia is reported in maximum number of cases of our study (7 out of 11).
In a study by Iran Sidhom et al., 105 cases were diagnosed with RMS in their hospital. The median age of diagnosis in their study was 3.6 years (range 2 months–17.7 years) mean 4.98 ± 4.1. In our study mean age group, was 3 years (range 1 to 15 years). The male to female ratio in his study was 2:1 whereas in our study ratio came out to be 0.4:1. Fifteen patients (14.3%) presented with an age < 1 years, 72 (68.6%) between 1 and 10 years, and 18 (17.1%) ≥ 10 years. The follow up period ranged 25–66 months with a median of 47.5 months.
Patients in our centre presented with age group between 1- 15 years, 4 cases being 1 year old, one was 2 years old, one was 3 years, another one 4 years, 2 cases 6 years, one 7 years and one 15 years old. The median age in the current study was 3 years.
In a study by Qualman et al. (2008) the soft tissue sarcoma committee of the Children's Oncology Group reported a higher rate of occurrence of focal or diffuse anaplasia in childhood rhabdomyosarcoma than previously reported in other studies. Anaplasia was noted in 13% of pathologic specimens of childhood rhabdomyosarcoma, focal in 7% and diffuse in 6%. In our study, anaplasia was diagnosed in 63.6% of the patients (7 out of 11), focal in 45.45% (5 cases) and diffuse in 18.18% (2 cases). Also Qualman et al. found that anaplasia was less common in younger age group but in our study it was found in younger patients as well.
The presence of anaplasia in RMS includes features such as increased nuclear size, marked cytological pleomorphism, numerous mitoses, and apoptotic bodies.
Few studies suggested that anaplasia in RMS could significantly affect outcome, however, it has not been included in the International Classification of Rhabdomyosarcoma (ICR) due to its apparent relative rarity.
The presence of anaplastic features has been known to correlate with poor clinical outcome in various pediatric malignancies, including Wilms tumor, and medulloblastoma., The presence of anaplasia in these 2 malignancies is associated with distinctive genetic abnormalities like the presence of large anaplastic cells is associated with a higher level of ERBBB2 expression and disruption of the p53-ARF tumor suppressor pathways medulloblastoma and anaplastic Wilms tumor are often found to be associated with p53 gene mutations. Defined similarly like in Wilms tumor, anaplasia in embryonal RMS consists of large, lobate, hyper chromatic nuclei with or without large atypical mitotic figures. Embryonal RMS with prominent degree of anaplasia are rare. In the present study focal anaplasia was reported in one case of Embryonal RMS. Though some of them are difficult to differentiate from pleomorphic RMS, the presence of more common striations help in diagnosis. Survival of patients with diffuse anaplastic embryonal RMS is similar to that of unfavorable survival of Pleomorphic RMS patients.
In the study conducted by Stephen Qualman, genomic hybridization analyses revealed that some genetic modifications were seen in embryonal tumors with anaplastic features and alveolar tumors. The principle genes involved (eg, IGF1R, MYCN) are linked with poor outcome and indicate that further studies should be carried out to look for this phenomenon.
As regards rhabdomyosarcoma, Kodet et al. reported that rhabdomyosarcoma patients with diffuse anaplasia had a worse clinical outcome. In contrast, Qualman et al. reported that the presence of anaplasia regardless of its distribution (focal or diffuse), had minimal effect on the the failure-free survival rate (63% vs 77% at 5 years) and overall survival (68% vs 82% at 5 years) rates in patients with embryonal rhabdomyosarcoma.
Furthermore, the outcome (favorable or unfavorable) of the tumor also depends on the site of the tumor. Favorable sites include non parameningeal head and neck, orbit, genitourinary (non-bladder, non-prostate, non-kidney) and biliary tract. Unfavorable sites include bladder, prostate, extremity and parameningeal.
As seen in literature that anaplasia is associated with genetic abnormalities and has a deleterious effect on the outcome of the patient, therefore cytogenetic studies should be conducted and anaplasia should be studied. However, we couldn't perform the cytogenetic studies because of lack of facilities in our setup and couldn't correlate anaplasia with the clinical outcome of the patients because of loss of follow up due to widespread COVID pandemic situation.
| Conclusion|| |
The tumors exhibiting anaplasia (focal or diffuse) are found to be associated with genetic abnormalities, necessitating cytogenetic study of RMS. This would facilitate future research on archival samples and may identify novel mechanisms of rhabdomyosarcoma tumorigenesis. Due to lack of facilities in our setup and the onset of pandemic further steps could not be taken to bring the study to a definite conclusion. Based on the results of the various research studies it has been demonstrated that anaplasia is a pathologic feature that can affect the outcome of the patient, and its presence should be prospectively mentioned in pathology reports. Therefore, we suggest that larger trials should be conducted to confirm whether the role of anaplasia as an independent prognostic factor in patients with intermediate risk embryonal histology disease is significant or not and to assess to include Anaplasia in latest classification of pediatric rhabdomyosarcoma.
The study was granted exemption by the institutional research ethics committee of Maulana Azad Medical College, on the grounds of research involving the collection or study of existing data and diagnostic specimens, vide (F.1/IEC/MAMC/80/80/2020/No. 323).
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Pathology, Associate Professor, Department of Pathology, Maulana Azad Medical College, Bahadur Shah Zafar Marg, New Delhi - 110 002
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2]