Year : 2009 | Volume
: 52 | Issue : 4 | Page : 540--542
Adenoid cystic carcinoma of the external auditory canal: Report of two cases
Supreeta P Nayak, Vaishali A Walke, Satish B Helwatkar, Sudhakar K Bobhate
Department of Pathology, Government Medical College, Nagpur, India
Supreeta P Nayak
C/o Mr. C.Wankhede, 15-Nargundkar Colony, Khamla Road, Nagpur-440 015
Adenoid cystic carcinoma occurring in the external auditory canal is very rare. Two cases are being reported. One was diagnosed on cytology based on which surgery was planned. In the second case, fine needle aspiration procedure had to be abandoned due to severe pain and a biopsy was required for its diagnosis. Morphologically, it resembles its more common salivary gland counterpart. Though severe pain during needling may be a limiting factor, adenoid cystic carcinoma of external auditory canal can be confidently diagnosed on cytology based on which surgical management can be planned.
|How to cite this article:|
Nayak SP, Walke VA, Helwatkar SB, Bobhate SK. Adenoid cystic carcinoma of the external auditory canal: Report of two cases.Indian J Pathol Microbiol 2009;52:540-542
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Nayak SP, Walke VA, Helwatkar SB, Bobhate SK. Adenoid cystic carcinoma of the external auditory canal: Report of two cases. Indian J Pathol Microbiol [serial online] 2009 [cited 2020 Aug 12 ];52:540-542
Available from: http://www.ijpmonline.org/text.asp?2009/52/4/540/56157
Malignant tumors of the external auditory canal (EAC) are rare with squamous cell carcinoma being the commonest. Those of glandular origin comprise just 20% of EAC tumors, with adenoid cystic carcinoma (ACC) of EAC being exceedingly rare. ,, Extensive search of English literature for the cytodiagnosis of ACC of the EAC yielded just one case report.  We present two cases of this rare condition. One was diagnosed on fine-needle aspiration (FNA) cytology, while in the second case, the FNA procedure had to be abandoned due to severe pain and the diagnosis was made on tissue biopsy.
A 38-year-old male presented with complaints of pain in the right ear of 6 months duration. On examination, a nodule of approximately 1.5Χ1.5 cms was seen occluding the EAC [Figure 1].
Computed tomography (CT) of temporal bone showed ill-defined, moderately enhancing, soft tissue lesion involving the inferior aspect of right EAC.
FNA was done under direct visualization.
Cytology findings: Smears showed uniform, cells arranged in tri-dimensional aggregates and dispersed singly. The cells were small with scanty cytoplasm, hyperchromatic nuclei, and occasional small nucleoli. The cells were seen to be clustered around and adherent to numerous globules [Figure 2]. These variably sized homogeneous, hyaline stromal globules (basement membrane material) appeared pale and semi-translucent with Papanicolaou and Haematoxylin and Eosin stains and dense, bright pink with May-Grunwald Giemsa stain. Branching finger-like structures of similar material with adherent cells were also seen. A cytodiagnosis of adenoid cystic carcinoma of the external auditory canal was offered.
A wide local excision along with parotidectomy followed and histopathology of the specimen confirmed the diagnosis. No parotid involvement was seen.
A 32-year-old female presented with left ear pain of one-year duration and a gradually increasing swelling in the left EAC since four months.
CT of temporal bone revealed circumferential soft tissue attenuated lesion involving the cartilage part and extending partly into the left bony EAC and laterally reaching up to tragus.
FNA was tried but abandoned as the patient complained of severe pain that radiated along the left side of the face. A biopsy of the EAC mass was done.
Histopathology findings: Tumor cells were in sheets and showing cribriform pattern with scant intervening stroma. The cells were basaloid, having scanty cytoplasm and hyperchromatic nuclei [Figure 3]. The lumina in the cribriform areas contained eosinophilic basement membrane - like material that was Periodic Acid Schiff (PAS) - positive. Few areas of necrosis were noted. A histopathological diagnosis of adenoid cystic carcinoma of the external auditory canal was offered. This was followed by complete resection of the remaining tumor mass with wide surgical margins.
ACC of EAC originates from the ceruminous glands located in the external ear and this has been confirmed by immunohistochemical and electron microscopic studies. ,, Ceruminous glands are apoeccrine in nature. Initially all tumors were designated as 'Ceruminoma' irrespective of their benign or malignant potential. But ceruminous gland tumors have now been classified with ACC being one of its types. ,
Majority of the cases present with severe ear-pain of prolonged duration and a mass or nodule in the ear canal.  The clinical presentation was similar in both the present cases. The cause of ear-pain can be explained by the propensity of ACC for early perineural involvement. This also explains the severe radiating pain that lead to FNA being abandoned in the second case. It has been proposed that this tendency for perineural involvement is related to the expression of neural cell adhesion molecules by the tumor cells of ACC. This accounts for most cases of intracranial involvement by this tumor due to direct extension along the nerves. 
The treatment of ACC includes complete surgical resection with wide margins. However, perineural involvement may cause difficulty in achieving clear surgical margins leading to local recurrences. Apart from surgical margins, involvement by the tumor of parotid, nerve and bone are important prognostic factors. , ACC is usually aggressive and invades locally. Metastases to regional lymph nodes and distant sites are well-documented. ,, Most recurrences have been reported within 2 years of treatment, but the interval between initial treatment and recurrence may extend even up to 14 years. Hence, long-term follow-up is advised. ,
In conclusion, though severe pain during needling may be a limiting factor, ACC of EAC can be confidently diagnosed on cytology based on which surgical management can be planned.
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