[1293] Mucosal Microcystic Adnexal Carcinomas of the Head and Neck: A Report of 4 Cases

Anne M Mills, Maria L Policarpio-Nicolas, Stacey E Mills. University of Virginia, Charlottesville, VA; University of Texas Health Science Center at San Antonio, San Antonio, TX

Background: Microcystic adnexal carcinoma (MAC) is a rare neoplasm occurring predominantly in the centrofacial skin of middle-aged patients. MACs demonstrate a stereotypic morphology with minimally atypical cells arranged in angulated ducts percolating through densely sclerotic stroma. Despite their bland appearance, these tumors show extensive invasion, local destruction, and are prone to recurrence. Their identification is frequently straightforward in the facial skin, but they pose significant diagnostic difficulties when they arise in alternate locations. On our consultation service, we have encountered several diagnostically challenging cases of MAC occurring in the head and neck. To our knowledge, there has only been a single report (Schipper et al, 1995) of this tumor occurring in the tongue and one report from the parotid gland (Hunt et al 1995). We know of no prior reports of MAC arising in the nasopharyngeal area or clivus.
Design: The University of Virginia Department of Pathology internal and consultative files were searched for all cases of MAC arising in the head and neck between 12/2003 and 9/2012.
Results: Four consultation cases were identified (Table 1). Each case demonstrated infiltrating cords, islands, and tubules comprised of minimally atypical cuboidal cells with round to oval nuclei and fine chromatin. Nucleoli were rarely prominent and mitotic figures were infrequent. Desmoplastic stroma was consistently evident in the background. Perineural invasion was identified in two cases, and three cases showed invasion of the skeletal muscle. One case closely abutted a minor salivary gland.

Table 1
Case #Patient AgePatient SexTumor LocationPresentation
141FBase of tongueTongue mass
247FAnterior tongueTongue lesion
373MNasopharynx, clivusDiplopia for 8 months
454FFloor of mouthFloor of mouth lesion

Conclusions: MAC may rarely arise in the nasopharynx and oropharynx. Including MACs on the differential diagnosis for gland-forming lesions of these sites is critical because while their remarkably bland histology lends itself to misclassification as benign, their behavior is locally aggressive. Desmoplastic stroma is a useful diagnostic aid and perineural and skeletal muscle invasion may be seen but are not requisite for diagnosis. MACs in this location may also mimic malignant salivary gland tumors including adenoid cystic carcinoma, polymorphous low grade tumor, and low grade adenocarcinoma, non-intestinal type.
Category: Head & Neck

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 149, Tuesday Morning


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