PhiliPPine Journal of otolaryngology-head and neck Surgery Vol. 29 no. 2 July – december 2014 PhiliPPine Journal of otolaryngology-head and neck Surgery 39 UNDER THE MICROSCOPE A 60-year-old woman with a 3-year history of a gingivoalveopalatal mass underwent an incision biopsy. Microscopically, the lesion centered in the stroma is infiltrative (Figure 1) and architecturally diverse, having cystic (Figure 2), linear or “Indian file” (Figure 3), solid and tubular (Figure 4) patterns. The cells are uniform in size, round to oval and have bland cytologic features with vesicular nuclei and inconspicuous nucleoli (Figure 4). The clinical data and histomorphologic features characterized by architectural diversity yet cytologic blandness lead us to the diagnosis of polymorphous low-grade adenocarcinoma. Polymorphous Low-Grade Adenocarcinoma Correspondence: Dr. Jose M. Carnate, Jr. Department of Pathology College of Medicine, University of the Philippines Manila 547 Pedro Gil St. Ermita, Manila, 1000 Philippines Phone (632) 526 4450 Telefax (632) 400 3638 Email: jmcjpath@gmail.com Reprints will not be available from the authors. The authors declared that this represents original material that is not being considered for publication or has not been published or accepted for publication elsewhere, in full or in part, in print or electronic media; that the manuscript has been read and approved by the authors, that the requirements for authorship have been met by the authors, and that the authors believes that the manuscript represent honest work. Disclosures: The authors signed a disclosure that there are no financial or other (including personal) relationships, intellectual passion, political or religious beliefs, and institutional affiliations that might lead to conflict of interest. Philipp J Otolaryngol Head Neck Surg 2014; 29 (2):39-40 c Philippine Society of Otolaryngology – Head and Neck Surgery, Inc. Joy B. Bernido, MD1 Jose M. Carnate, Jr., MD2 1Department of Laboratories Philippine General Hospital University of the Philippines Manila 2Department of Pathology College of Medicine University of the Philippines Manila Figure 1. Hematoxylin and Eosin (40x) Tumor within the stroma with an infiltrating growth pattern Figure 2. Hematoxylin and Eosin (100x) Tumor showing tubules and small cystic structures. (Hematoxylin and Eosin, 40x) (Hematoxylin and Eosin, 100x) PhiliPPine Journal of otolaryngology-head and neck Surgery Vol. 29 no. 2 July – december 2014 UNDER THE MICROSCOPE 40 PhiliPPine Journal of otolaryngology-head and neck Surgery REFERENCES Luna MA, Wenig BM. Polymorphous low-grade adenocarcinoma. In: Barnes L, Eveson JW, 1. Reichart P, Sidransky D, editors. World Health Organization Classification of Tumors: Pathology and Genetics of Head and Neck Tumors. Lyon, France: International Agency for Research on Cancer Press, 2005. Pintor MF, Figueroa L, Martinez B. Polymorphous low-grade adenocarcinoma: review and case 2. report. Med Oral Patol Oral Cir Bucal. 2007 Dec 1; 12(8):E549-51. Thompson LDR. Polymorphous low-grade adenocarcinoma. 3. Pathology Case Reviews 2004 Nov- Dec;9(6): 259-263. doi: 10.1097/01.pcr.0000143777.ea Olusanya AA, Akadiri OA, Akinmoladun VI, Adeyemi BF. Polymorphous low grade 4. adenocarcinoma: literature review and report of lower lip lesion with suspected lung metastasis. J Maxillofac Oral Surg. 2011 Mar; 10(1): 60-63. doi: 10.1007/s12663-011-0185-1. Seethala RR, Johnson JT, Barnes EL, Myers EN. Polymorphous low-grade adenocarcinoma: the 5. University of Pittsburgh experience. Arch Otolaryngol Head Neck Surg 2010 Apr;136(4):385-92. doi: 10.1001/archoto.2010.39. De Araujo VC, Passador-Santos F, Turssi C, Soares AB, de Araujo NS6. . Polymorphous low-grade adenocarcinoma: an analysis of epidemiological studies and hints for pathologists. Diagn Pathol 2013 Jan 15;8:6. doi: 10.1186/1746-1596-8-6. Potluri A, Prasad J, Levine S, Bastaki J. Polymorphous low-grade adenocarcinoma: a case report. 7. Dentomaxillofac Radiol 2013;42(2):14804843. doi: 10.1259/dmfr/14804843. Gnepp DR, editor. Diagnostic surgical pathology of the head and neck. 28. nd ed. Philadelphia: Saunders Elsevier, 2009, p. 486-489. Polymorphous low-grade adenocarcinoma (PLGA) is a malignant epithelial tumor characterized by cytologic uniformity, morphologic diversity, an infiltrative growth pattern and low metastatic potential.1 It is the second most common intraoral malignant salivary gland tumor1 following mucoepidermoid carcinoma. The tumor is found almost exclusively in minor salivary glands and is rare in extraoral locations including major salivary glands.2 The tumor affects a wide age range (16 – 95 years; mean 60 years) with only two pediatric cases reported1 and has a female predilection.3,4 It usually presents as a painless mass located within the oral cavity3 60% of which are located in the palate.1 They are characteristically unencapsulated although well-circumscribed.3 This entity is architecturally diverse (“polymorphous”) even within a single tumor, with solid, tubular, trabecular, cribriform, papillary and Figure 3. Hematoxylin and Eosin (100x) Tumor cells showing a linear (“Indian-file”) arrangement (Hematoxylin and Eosin, 100x) Figure 4. Hematoxylin and Eosin (400x) The round to oval tumor cells are uniform in size with bland nuclei and inconspicuous nucleoli (Hematoxylin and Eosin, 400x) linear patterns being described. Perineural invasion is common although it was not seen in this case. The tumor cells are small to medium sized and uniformly round to polygonal. The nuclei are bland and vesicular with occasional small inconspicuous nucleoli. Mitotic figures can be found occasionally but are never numerous.3, 8 The morphologic heterogeneity in small biopsies and frozen section samples can be confused with pleomorphic adenoma and adenoid cystic carcinoma.6,7 Glial fibrillary acid protein may help as PLGA is typically non-reactive in contrast to pleomorphic adenoma.2 De Araujo and others site that uniformly positive vimentin, CK7 and S100 staining favors PLGA over adenoid cystic carcinoma.6 Tumor cytology and histology are quite characteristic - recognizing the constant cytological appearance despite the diversity of architectural tumor patterns should aid one in diagnosing PLGA. PLGA, despite its infiltrative growth pattern and propensity for perineural invasion usually runs an indolent course. Nodal metastasis and distant spread are rare, occurring in less than 1% of cases.4 Seethala and others report that extrapalatal location is associated with a more aggressive clinical course.5 Complete surgical excision is the primary treatment with neck dissection reserved for nodal metastasis.1 One- third of patients may have a local recurrence and lifelong monitoring is suggested. Re-excision is amenable in these cases.5,6