Case of the week Details

• Heterogeneously enhancing destructive mass lesion centred at right superior maxillary alveolus with involvement of ipsilateral superior gingiva-buccal sulcus and hard palate.
• Smooth widening of the right greater palatine foramen. Enhancing soft tissue thickening with widening of right pterygopalatine fossa (PPF). 
• Smooth expansion of right vidian canal, foramen rotundum and infraorbital canal with enhancing soft tissue in the inferior aspect of right cavernous sinus. 

DIAGNOSIS:

Right maxillary alveolus carcinoma with perineural spread along V2 and its branches.

DISCUSSION:

Head and neck malignancies showing propensity for perineural spread include:

• Squamous cell carcinoma.
• Adenoid cystic carcinoma.
• Malignant desmoplastic melanoma.
• Basal cell and adenocarcinoma.

Modalities for diagnosis:

• CT has low sensitivity. Bony foramina better evaluated.
• MRI is the preferred modality due to superior soft tissue contrast.
• Gadolinium-MR makes the diagnosis by showing enlargement and abnormal contrast enhancement, which cannot be depicted with CT.

Indicators of perineural spread:

• Effacement of perineural, foraminal and/or juxtaforminal fat
• Asymmetric nerve or foraminal enlargement
• Asymmetric, irregular or nodular nerve enhancement
• Secondary features of denervation injury including acute edema and chronic atrophy.

Key anatomic landmarks:

• V1: Supraorbital foramen.
• V2: Infraorbital foramen, pterygopalatine fossa, vidian canal, foramen rotundum, greater and lesser palatine foramen (As in our case).
• V3: Mental foramen, mandibular canal, mandibular foramen, foramen ovale.
• Geniculate ganglion: Enlargement and obliteration of the geniculate fossa.
• Facial nerve: Mastoid segment and stylomastoid foramen.
• Hypoglossal nerve: Hypoglossal canal.
• Perineural spread of malignancy is a potential and important route of spread of head and neck malignancies; its presence indicate a poor prognosis. Perineural spread often have tumor recurrence and poor long-term survival.
• A checklist approach and thorough inspection of potential sites on contrast enhanced fat-suppressed images should be routinely undertaken.
• Presence of focal neurological deficits and cranial nerve palsies in patients with head and neck malignancies should prompt a detailed search to exclude perineal spread of malignancy.

Differential diagnosis:

1. Primary neural tumours such as schwannomas.
2. Invasive fungal infections such as aspergillosis or mucormysosis (in severely immunocompromised individuals).
3. Meningeal inflammatory disorders such as sarcoidosis or histiocytosis.

REFERENCES:

1. Perineural spread of malignant head and neck tumors: review of the literature and analysis of cases treated at a teaching hospital. Mauro César Silveira Moreira, Antonio Carlos dos Santos, Murilo Bicudo Cintra. Radiol Bras. 2017 Sep-Oct; 50(5): 323–327.
2. Perineural Tumor Spread in Head and Neck Malignancies, Seminars in Roentgenology, Volume 54, Issue 3, 2019, Mohit Agarwal, Pattana Wangaryattawanich, Tanya J. Rath.
3. Perineural spread in head and neck malignancies, Radiation Medicine volume 24, pages1–8(2006). Ojiri, H.
4. Ong CK, Chong VH. Imaging of perineural spread in head and neck tumours. Cancer Imaging. 2010;10(1A):S92.

Dr. Bhupendar Singh
Radiology Resident,
Manipal Hospitals Radiology Group

Dr. Anita Nagadi
MD, MRCPCH (UK), FRCR (UK), CCT (UK)
Senior Consultant Radiologist
Manipal Hospitals Radiology Group.