A rare case of paediatric oral rhabdomyosarcoma presenting with respiratory distress

Oral rhabdomyosarcoma is an extremely rare clinical entity with gross underreporting in medical literature. This case presented with an atypical clinical presentation of respiratory distress hitherto unreported in the medical literature. The case also highlights the importance of complete surgical excision in management which eliminates radiotherapy.

A three-year-old child reported to our paediatric casualty with stridor and respiratory distress for the last 12 hours. Oral cavity examination revealed a pinkish large ovoid, proliferative and multilobular lesion of 3 cm in diameter with no ulcers (Figure 1A). The swelling was firm, tender, friable and bled on touch. It was however difficult to discern the site of origin of the said lesion, and the lower airway was not amenable to examination (obscured by the lesion). A detailed clinical evaluation revealed that there had been an insidious growth of this lesion for the last 6 months causing difficulty in breathing and episodes of sleep apnoea. The patient’s condition deteriorated over a period of time, and corona pandemic mitigated timely medical advice. Clinically, a differential diagnosis of reactive and benign mesenchymal lesions was considered.OPEN IN VIEWER

An immediate CT scan was done: large lobulated heterogeneously enhancing lesion was visualized in the oropharyngeal region, extending from the palate to C5 level, measuring 3.9 x 2 x 3.7 cm (Figure 1B). As the mass precluded endotracheal intubation, an urgent tracheostomy with excisional biopsy of the lesion was done after requisite investigations. The proliferative mass was seen to be arising from the soft palate and was removed in toto. The surgery was uneventful with no post-operative complication. The patient was subsequently discharged with extubation and closure of the tracheostomy site on the 10^th post-op day.

Histopathological examination revealed multiple bits of round and oval spindle-to-stellate cells lined by stratified squamous epithelium and subepithelial ‘Cambium’ layer (Figure 2). Cells had finely granular chromatin and oval prominent nucleolus (Figure 2). Stroma was myxomatous. Immunohistochemistry was positive for MYO-D1, myogenin and desmin, but negative for CK, thereby confirming the diagnosis of botryoid RMS (Figure 3).OPEN IN VIEWER

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Figure 3.

Immunocytochemistry: (A) positive for MYO-D1, (B) positive for myogenin, (C) positive for desmin, and (D) negative for CK.

With the aforementioned diagnosis, in accordance with the protocol of management of localized low risk rhabdomyosarcoma, chemotherapy with vincristine (1.5 mg/m²) and actinomycin D (1.5 mg/m²) was initiated in 8 cycles extending over 22 weeks.^1,2 The patient was kept under regular follow-up for a duration of 1 year thereafter and stands cured with no untoward incident to report.

RMS is a mesenchymal malignant neoplasm with skeletal muscle differentiation. Though RMS is a common malignant tumour in children, yet it is particularly rare in oral and perioral regions.^3,4 Interestingly, the first case of RMS was reported by Weber (1854) in the oral cavity (tongue). ⁵ The literature shows male preponderance with a male:female ratio of 2.1:1. ⁶ There are no specific aetiological factors associated with it, but recent review of the literature cites distinct cytogenetic findings: trisomies of 2, 8, 13 and molecular studies commonly show allelic loss of 11p15. ⁷ Based on the location in the head and neck region, the tumour may be classified as orbital, superficial and parameningeal. Histopathologically, it is classified as embroynal, botryoid, alveolar and pleomorphic varieties.^3,4,7,8 Immunohistochemistry clinches the diagnosis as in this case.^3,7 Treatment regimens include surgery, chemotherapy and radiotherapy, and are based on Intergroup Rhabdomyosarcoma Study (IRS)/COG guidelines.^1-4,7 This tumour commonly metastasizes to the lungs, lymph node and bone marrow. ⁸ The cause of death is tumour progression and involvement of adjacent structures. ⁹ It would be pertinent to note that botryoid variant has a nearly 90% survival rate. ⁷

This case merits mentions on many accounts: firstly, the occurrence in a female patient and secondly, the rarity of the tumour in the soft palate (tongue being the commonest site in this relatively uncommon tumour of the oral cavity). ⁹ Thirdly, the clinical presentation was atypical with apnoea and respiratory distress as the pedicled mass blocked off the oropharynx completely during breathing. Mostly, these cases in the head and neck region present as painless swellings with rapid growth and ulceration usually causing facial asymmetry.^3,7 This is probably the first reported case of oral rhabdomyosarcoma to present with respiratory distress, warranting tracheostomy in the medical literature. Lastly, the said case also delineates the importance of complete excision of the lesion (palate being an accessible surgical site) which leads to avoidance of radiotherapy and its complications with no compromise in survival as proposed by Daya et al. ¹⁰ Furthermore, the case also highlights the detrimental effect of this dreadful pandemic on other diseases, as it led to delay in seeking medical advice.

The aforementioned factors make this clinical record unique and thus prompted us to share our modest experience on the cited subject.