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Polymorphous Low-Grade Adenocarcinoma of the Lacrimal Gland
Arch Ophthalmol. 2004;122:915-917.
Malignancies constitute half of all epithelial tumors of the lacrimal gland, with the majority being adenoid cystic carcinoma. Adenocarcinomas are much less common and generally demonstrate a poor prognosis. However, the recent application of histological subtyping to this group is leading to a better characterization of what appears to be a heterogeneous collection.1 We present a rare case of polymorphous low-grade adenocarcinoma (PLA) of the lacrimal gland and discuss the clinical manifestation and prognosis in the context of similar tumors arising within the salivary glands.
Report of a Case
A 67-year-old man was initially seen with painless right upper eyelid swelling and conjunctival hyperemia across a 2-day period. The patient had been previously asymptomatic, and old photographs were not available for review. Examination revealed him to be afebrile with a visual acuity of 6/12 OD and 6/9 OS, 6 mm of proptosis, 3-mm inferior globe displacement, temporal conjunctival hyperemia, and a tender mass in the superotemporal orbit. Extraocular movements were limited in lateral and up gazes. The erythrocyte sedimentation rate was 61 mm/h and white blood cell count, 13 200/µL (13.2 x 109/L). Computed tomography findings showed an ill-defined mass in the lacrimal gland with a central radiolucency, rim enhancement, and no bony changes (Figure 1).
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Figure 1. Axial computed tomographic scan shows a mass in the right lacrimal gland with a central radiolucent area.
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The mass was surgically explored via a skin-crease incision and appeared to consist of an abscess containing yellow-green viscous material. A culture yielded no growth, but biopsy findings of the cavity wall revealed adenocarcinoma thought to represent a primary lacrimal neoplasm rather than metastasis because the tumor expressed both cytokeratins (CAM 5.2) and S100 protein immunoreactivity. This immunoprofile, while not diagnostic, is typical of salivary gland tumors including PLA.2
The patient underwent thorough systemic evaluation, including computed tomography of the chest, abdomen, and head. All investigation results were normal, and a lid-sparing exenteration, including the biopsy track, was performed.
Results
Histopathologic results revealed PLA of the lacrimal gland (Figure 2). The tumor cells were cytologically bland, showing mild nuclear pleomorphism, and no mitoses were identified. However, there was extensive infiltration of the adjacent tissue, and the tumor displayed a variety of architectural patterns, including cribriform, tubular, and fascicular areas along with solid cell nests. Some necrosis was seen centrally, and infiltration of the extraocular muscle was present. However, there was no perineural or vascular invasion or evidence of encapsulation, and the residual gland was atrophic with evidence of chronic inflammation and fibrosis. The patient made a good recovery and at last follow-up, 6 years after initial examination, there was no recurrence.
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Figure 2. Histological appearance of the mass from our patient. A, Hematoxylin-eosin section demonstrates uniform cells in a cribriform pattern with infiltration of the margin (original magnification x20). B, On higher power, the tumor cells are seen to be cytologically bland with only mild nuclear polymorphism (hematoxylin-eosin, original magnification x400).
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Comment
Adenocarcinomas constitute 5% to 7% of epithelial tumors arising in the lacrimal gland.3-4 Until recently, these neoplasms were considered a single entity, classified under the rubric of "adenocarcinoma" or "adenocarcinoma not otherwise specified." The advent of the World Health Organization Classification of Salivary Gland Adenocarcinomas5 proffered a framework for the categorization of these uncommon lacrimal tumors. This classification system is of significance because certain subtypes are associated with differing biologic behaviors and outcomes. Three of these subtypes, salivary duct carcinoma, epithelial-myoepithelial carcinoma, and PLA, have been reported within the lacrimal gland.
The histological subtype of PLA seen in our case occurs almost exclusively in the minor salivary glands and is distinguished by cytologically bland, uniform cells with few or no mitoses. These cells assume a variety of growth patterns including cribriform areas, solid nests, tubular regions, clusters, and "Indian file" columns. The cribriform areas are distinguished from adenoid cystic carcinoma by the relative lack of atypia of the component cells. In contrast to pleomorphic adenomas, PLAs show infiltration into adjacent tissues as well as a propensity for perineural invasion.5-6
Within the lacrimal gland, PLA has only been reported on one previous occasion. Ni et al7 mentioned 3 cases in their series of 272 epithelial lacrimal tumors but did not document clinical manifestation, management, or outcome. The clinical manifestation of our patient was distinctly unusual for an epithelial malignancy of the lacrimal gland. While inflammatory manifestations have been described in a few benign mixed tumors, usually on the basis of mucinous cyst rupture, such a manifestation for malignant epithelial tumors is distinctly rare. Mucoepidermoid carcinomas in the lacrimal gland rarely cause inflammation, but with regard to adenocarcinomas, an acute inflammatory process has not previously been described. Heaps et al,8 in a series of 13 lacrimal adenocarcinomas, found a palpable mass, proptosis, and pain to be the most common manifestation.
In our case, the constellation of acute inflammation in conjunction with the central low-density area on computed tomographic scan was suggestive of a lacrimal abscess. However, the absence of growth in the necrotic cavity contents militated against an infective etiology. In addition, the central area was neither mucinous nor hemorrhagic, leading us to postulate a mechanism of central necrosis secondary to infarction to account for both the inflammatory response and the radiological appearance.
While microscopic focal necrosis has been described in PLA, the occurrence of significant central cavitation is unusual behavior in a low-grade tumor.9 In fact, within the orbit, central necrosis is generally a feature of aggressive, rapidly growing malignancies such as sarcomas or metastases. In comparison, PLA arising in the salivary glands has an indolent growth pattern and a relatively low incidence (6.5%) of metastasis to the regional lymph nodes.10 Local recurrence occurs in 22% but can usually be managed by further resection. Distant metastasis or death due to tumor is extremely rare, and as a consequence, PLA has a much better prognosis than other salivary adenocarcinomas.10
The extrapolation of the course of salivary gland PLA to those originating in the lacrimal gland was one of the factors considered in treating our patient. Although exenteration followed by radiotherapy has been advocated for lacrimal adenocarcinomas as a group,8 we elected to treat with exenteration alone on the basis of the known behavior of this tumor. This was in concordance with the management of salivary PLA, which carries an excellent long-term survival rate following local excision alone. Conversely, lacrimal tumors designated as lacrimal adenocarcinomas have, in general, a poor prognosis. In the Heaps et al8 series of 13 patients, 6 died and 3 had recurrent disease. Of the 4 recurrence-free patients, all had been treated with exenteration and radiotherapy. There was, however, no elucidation of histological subtypes in this series; thus, the guidelines for treatment of PLA in the lacrimal gland need further delineation. It is possible that given the favorable outcome of local resection for salivary gland PLA, a more conservative local resection with clear margins may have been adequate treatment in our patient. Nevertheless, some caution is justified in extrapolating management as well as classification from salivary gland tumors to those of the lacrimal gland.
In conclusion, it is evident the difference between the poor outlook ascribed to adenocarcinoma of the lacrimal gland and the prognosis of PLA, at least in the salivary glands, justifies further characterization of this entity within the orbit.
The authors have no relevant financial interest in this article.
AUTHOR INFORMATION
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Dinesh Selva, MBBS(Hons), FRACS, FRANZCO;
Garry J. Davis, MBBS, FRACS, FRANZCO;
Tom Dodd, MBBS(Hons), FRCPA
Adelaide, Australia
Jack Rootman, MD, FRCSC
Vancouver, British Columbia
Corresponding author: Dinesh Selva, MBBS(Hons), FRACS, FRANZCO, Oculoplastic and Orbital Unit, Department of Ophthalmology, Royal Adelaide Hospital, Adelaide University, Adelaide, South Australia 5000 (e-mail: raheyes{at}mail.rah.sa.gov.au).
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SECTION EDITOR: W. RICHARD GREEN, MD
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