Teaching Case

A 6-year-old male patient presented to the emergency room with a history of headache for the past 6 months. The patient’s mother also complained of sudden increase in head circumference of the child. There was no significant past history. No previous investigation was done prior to this.

Non-contrast computed tomography of the brain showed well-defined solid cystic lesion in left fronto-parietal lobe with hyperattenuating solid component towards cortex, hypoattenuating cystic component towards white matter. Solid component also showed calcification. (Fig. 1a, b).

Contrast-enhanced CT showed peripheral enhancing cystic component, heterogeneously enhancing solid component. (Fig. 2a, b).

Magnetic resonance imaging showed similar findings with solid component appearing hypointense on T2, T1, FLAIR image (Fig. 3a, 4a, 5a), cystic component hyperintense on T2 and FLAIR, hypointense on T1 image (Fig. 3b, 3c, 4b, 4c, 5b, 5c).

Contrast-enhanced MRI showed peripheral enhancing cystic component, heterogeneously enhancing solid component. (Fig. 6a, 6b, 6c). Mild perilesional oedema, mass effect in form of compression of ipsilateral lateral ventricle and contralateral midline shift of 2.7 centimetres was noted (Fig. 2a, 2b).

T2*GRE image showed blooming in solid component corresponding to calcification (Fig. 7a, 7b)
No diffusion restriction was noted (Figure 8a, 8b).

Final diagnosis was confirmed on histopathology.

Desmoplastic infantile tumours {Desmoplastic infantile ganglioglioma (DIG) and desmoplastic infantile astrocytoma (DIA)} are rare supratentorial tumours of infancy [1]. They are most commonly seen in the first year of age but have been reported until up to 5 years of age [1]. They are as such benign lesions (WHO grade I malignancy) with aggressive-looking imaging findings [1]. Late presentation of DIG is less frequent with only 20 cases reported after 5 years of age [2]. There are at least 25 cases of DIG reported in the literature [3]. Male to female ratio is 2:1 [3].

The most common symptom is rapid increase in head circumference associated with tense bulging fontanelle. Seizures are an uncommon feature [3].

It is a neurepithelial tumour characterised by voluminous size, intense desmoplasia with a cystic component and astrocytic/ganglionic differentiation [4]. They present as large intracerebral mass (with median size measuring 8 cm) most commonly located in frontal and parietal lobes. The tumour shows an intense desmoplastic reaction at its periphery with attachment to dura and the presence of atypical/immature cellular tissue is the histologic hallmark of DIG and helps to distinguish it from a conventional ganglioglioma [3]. No cases of seeding through cerebrospinal fluid or any metastasis have been reported [3]

On imaging, the tumour is large, heterogeneous with solid and cystic components, the solid component appears hyperattenuating on CT and hypointense on T2, T1 and FLAIR, abutting the dura. The cystic component appears hypoattenuating on CT and hyperintense on T2, FLAIR and hypointense on T1 imaging. It is located adjacent to the white matter of the brain [4]. The solid component shows strong heterogeneous enhancement, the cystic component shows peripheral enhancement [4]. Adjacent meningeal thickening with enhancement may be noted in 50% of cases [1]. Bony remodelling in the form of bossing, thinning and deformation have also been reported in the literature [1]. The lesion may also show moderate vasogenic oedema and mass effect [3]. Presence of calcification is rare, which was noted in our case [1].

Since the tumours are graded as WHO grade I malignancy, total surgical excision of the tumour is the treatment of choice [2]. Illness-free periods encompass 8.3-20 years [2]. Occasionally, spontaneous regression has also been described [2]. Radiotherapy is been avoided as it can interfere with encephalic development of young patients [2].

In conclusion, typical imaging features of DIG are as mentioned above with complete surgical excision being the treatment of choice with excellent prognosis.