Aggressive Small Blue Round Cell Tumour of Craniomaxillofacial Region in a One-Year-Old Child: A Rare Finding

INTRODUCTION

The term, “Small Blue Round Cell Tumours” (SBRCT) is a heterogeneous group of highly aggressive malignant neoplasms which are composed predominantly of small and monotonous undifferentiated cells with high nucleocytoplasmic ratios, relatively small-sized nuclei, and scant cytoplasm.¹ This group includes diverse malignancies of epithelial, haematolymphoid, neuroectodermal, and mesenchymal origin. SBRCT of the craniomaxillofacial region is a very rare entity, showing rapid aggressive forms. Differential diagnosis of these SBRCTs is particularly difficult due to their undifferentiated nature. This group of SBRCTs includes Ewing’s Sarcoma, Primitive Neuroectodermal Tumour (PNET) or extraskeletal Ewing’s sarcoma, neuroblastoma (NB), rhabdomyosarcoma, desmoplastic small round cell tumour, non – Hodgkin’s lymphoma, small - cell osteosarcoma, small – cell carcinoma (either undifferentiated or neuroendocrine), olfactory neuroblastoma, mesenchymal chondrosarcoma, lymphoblastic leukaemia, and blastemic component of Wilms’ tumour. Their clinical presentations often overlap, and all these tumours have almost similar histologic appearance, thus making the accurate diagnosis very difficult.^[1-3]

CASE REPORT

A one-year-old male patient was brought by his parents with the chief complaint of painless swelling over the right side of his face for three months. There was no history of trauma to face. The patient was conscious, cooperative, and responding to verbal commands with spontaneous eye and motor response. Facial swelling started spontaneously and increased constantly to its present size in the last three months. No systemic illness was present, and the patient was hemodynamically stable. On clinical examination, marked facial asymmetry was present. Solitary swelling was present on the right side of the face, extending from the temporal region to the malar region supero-inferiorly and ocular region to post-auricular region anteroposteriorly, measuring approximately 9 cm × 8 cm in maximum dimensions [Figure 1a]. Skin over swelling was tense, with prominent vasculature, and no suppuration or blood discharge was present [Figure 1b]. On palpation, swelling was firm, non-tender, non-pulsatile, non-fluctuant, and non-compressible, with no surface rise of temperature. Subconjunctival oedema, proptosis, and medial displacement of the globe were present with respect to the right eye [Figure 1c]. Intraoral examination was insignificant, with no abnormality detected in the oral cavity. Fine needle aspiration cytology (FNAC) was performed [Figure 1d].

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Figure 1:

Clinical photographs (a) Solitary swelling present on the right side of the face, (b) Tense skin over swelling with prominent vasculature, (c) Subconjunctival oedema, proptosis, and medial displacement of globe with respect to the right eye, (d) FNAC performed. FNAC: Fine needle aspiration cytology.

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A computed tomography (CT) scan of the head, face, and neck was performed. It revealed a large-sized (9.1 cm×8.3 cm×7.8 cm) lesion arising from the right temporal and zygomatic region [Figure 2a]. Superiorly, the lesion was extending intracranially in the extradural plane of the right temporal and basitemporal region, measuring approximately 1.7 cm×1.9 cm×3.7 cm [Figure 2b]. Medially, it was extending into the right orbit in the extraconal region, causing compression over the right globe and extraocular muscles from the lateral aspect, causing proptosis of the right globe [Figure 2c]. Inferiorly, it was extending into the infratemporal fossa and encasing the coronoid process of the mandible [Figure 2d]. Laterally, it was causing diffuse bulge over the skin surface. There was destruction of the lateral wall of the right orbit, the lateral wall of the right maxillary sinus, the right zygomatic arch, and the greater wing of the sphenoid bone. Magnetic resonance imaging (MRI) of the head, face, and neck was also performed to identify any intraparenchymal changes within the brain. The dura mater was found intact in the right temporal and basitemporal region where the lesion was invading intracranially and having its intracranial extensions [Figure 3a]. The rest findings were similar and were co-relating with those of CT scan findings [Figure 3b-d]. All these findings were suggestive of a neoplastic mass with the possibility of soft tissue sarcoma. FNAC also reported a high-grade malignancy suggestive of SBRCT. The smear revealed neoplastic cells predominantly in dispersed sheets. These neoplastic cells were medium to large, having round to polygonal pleomorphic nuclei, fine chromatin, and 2-4 nucleoli. Multinucleated tumour giant cells with wreath-like nuclei were also present. Mitosis was atypical. Many of these cells showed eccentrically located nuclei with prominent nucleoli. Nuclear moulding was also noted. Incisional biopsy was performed, and the histopathological diagnosis confirmed SBRCT [Figure 4a and b]. The sections revealed vague nodules separated by ill-formed fibrocollagenous septa. These nodules comprised sheets of atypical cells admixed with many thin-walled hyalinised blood vessels. These cells are medium-to-large sized, having scanty indistinct cytoplasm, high N:C (nuclear-to-cytoplasm) ratio, and irregular, pleomorphic, hyperchromatic nuclei. True rosettes, multinucleated giant cells, and many apoptotic bodies were seen. An immunohistochemistry test was advised for the exact characterisation of the lesion. However, for unknown reasons, the parents did not report again, and the patient was lost to follow-up. Hence, further investigations (IHC- immunohistochemistry) and treatment could not be initiated.

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Figure 2:

Computed tomography scan images of head, face, and neck (a) Lesion arising from right temporal and zygomatic region, (b) Intracranial extension of the lesion in the extradural plane of the right temporal and basitemporal region, (c) Orbital extension of the lesion in the extraconal region causing compression over the right globe and extraocular muscles from the lateral aspect causing proptosis of the right globe, (d) Extension of the lesion into the infratemporal fossa and encasing the coronoid process of the mandible. CT: Computed tomography.

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Figure 3:

MRI images of head, face, and neck (a) Intact duramater in right temporal and basitemporal region where lesion was invading intracranially (Sagittal view), (b) Intracranial extension of the lesion in the extradural plane of the right temporal and basitemporal region (Coronal view), (c) Orbital extension of the lesion in the extraconal region causing compression over the right globe and extraocular muscles from the lateral aspect causing proptosis of the right globe, (d) Extension of the lesion into the infratemporal fossa and encasing the coronoid process of the mandible.

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Figure 4:

Histopathological features (a) Vague nodules separated by ill-formed fibrocollagenous septa. These nodules comprised sheets of atypical cells admixed with many thin-walled hyalinised blood vessels. True rosettes, multinucleated giant cells, and many apoptotic bodies were seen (H&E ×200), (b) Medium-to-large sized atypical cells having scanty indistinct cytoplasm, high N:C ratio and irregular, pleomorphic, hyperchromatic nuclei (H&E ×400). N:C: Nuclear-to-cytoplasm ratio, H & E: Haematoxylin and eosin.

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DISCUSSION

The family of tumours belonging to the group of SBRCT is characterised by high cellularity, small cell size, and a diffuse pattern of growth. The tumour cells have darkly staining nuclei and scanty cytoplasm, which gives an overall blue appearance in the haematoxylin and eosin (H&E) stained sections. The tumour cells are seen as round, slightly larger, or double the size of red blood cells in air-dried smears. These characteristics of tumour cells has led to the name “small blue round cell tumour”.^[1,4] Though these tumours can occur in any age group, D’Cruze L et al.^[1] documented that 44% of these cases occur in the 15-45 year age group, with a high male predisposition (74%). Also, these tumours rarely affect the head and neck regions.^[1] The tumour in early stages is asymptomatic and difficult to diagnose; it may cause massive swelling over the face with time. Oral, cutaneous, orbital, and cranial involvement can occur in the craniofacial region.^[3,5,6] An early and accurate diagnosis is mandatory to plan an appropriate treatment plan. Identification of the morphological features is difficult if the tumour is poorly differentiated or undifferentiated; therefore, no definitive diagnosis can be reached. FNAC and incisional biopsy play an important role in the initial diagnosis of these tumours. For exact categorisation, IHC and chromosomal study play a crucial role. The pathologist has to judiciously correlate clinical, radiological, and histological findings with a panel of IHC markers.^[1,4,5] A panel of antibodies that recognise several tumour-associated markers is used for differential diagnosis. These constitute neuron-specific enolase and GD2 present in NB and, sporadically, in osteosarcomas and rhabdomyosarcomas; CD99 expressed by Ewing’s sarcoma and sometimes by PNETs; and desmin and cytokeratin present in desmoplastic tumours.^[7] In the chromosomal study, the tumour typically shows a recurrent chromosomal translocation.^[6]

The treatment protocol of SBRCT has not yet been established. The treatment approach is radical and multimodal, comprising surgery, chemotherapy, and radiotherapy, depending on tumour size and location, although prognosis remains very poor.^[6] Lal et al. reported that treatment with chemotherapy, surgery, and radiotherapy conferred a 3-year survival of 55% compared to 27% for those who did not receive all three treatments.^[8] Early and extensive surgical excision (excision with 2–3 cm tumour-free margin) is important. Debulking surgery (excision of at least 90% of tumour mass) can also be considered in case the tumour occupies inaccessible or inoperable sites. Gross tumour excision provides better survival (3-year survival of 58% compared to 0% in non-resected cases).^[9] Adjuvant chemotherapy regimens containing agents such as vincristine, doxorubicin, and cyclophosphamide and/or adjuvant radiotherapy are also recommended in patients who are diagnosed at an early stage.^[10]

CONCLUSION

Although the prognosis of SBRCT is poor, a definite diagnosis and correct treatment plan should be formulated at the latest for increased survival in cases of such rare and atypical tumours. The best treatment is early surgical excision and adjuvant chemoradiotherapy.