AJR 2002; 178:1563-1565
© American Roentgen Ray Society
Long-Standing Mucosa-Associated Lymphoid Tissue Lymphoma of the Parotid Gland: CT and MR Imaging Findings
B. B. Tagnon1,
I. Theate2,
B. Weynand2,
M. Hamoir3 and
E. E. Coche1
1 Department of Radiology, Cliniques Universitaires St-Luc, Université
Catholique de Louvain, Ave. Hippocrate, 10, B-1200 Brussels, Belgium.
2 Department of Pathology, Cliniques Universitaires St-Luc, Université
Catholique de Louvain, B-1200 Brussels, Belgium.
3 Department of Head and Neck Surgery, Cliniques Universitaires St-Luc,
Université Catholique de Louvain, B-1200 Brussels, Belgium.
Received July 20, 2001;
accepted after revision October 23, 2001.
Address correspondence to E. E. Coche.
Introduction
Mucosa-associated lymphoid tissue (MALT) neoplasms are extranodal
non-Hodgkin's lymphomas. The most common site of the MALT lymphoma is the
gastrointestinal tract. However, these tumors have been reported to occur in
the salivary glands, lung, skin, soft tissues, breast, thyroid gland, thymus,
and ocular adnexa and orbit
[1]. To our knowledge, no
previous report has been dedicated to CT and MR imaging findings of MALT
lymphoma of the parotid gland in adults. We report a case of unilateral
long-standing MALT lymphoma occurring in an adult and presenting as a
partially calcified swollen parotid gland.
Case Report
A 67-year-old man presented with a painless, slowly progressive left
parotid swelling of 9 years' duration. The patient was a former smoker;
findings on HIV serology were negative. The patient had consulted the oral
surgery department 2 years previously because of dis-satisfaction with his
appearance. Clinical examination revealed a firm, fixed mass in the left
parotid gland that measured 60 x 35 mm. MR imaging showed diffuse left
parotid gland enlargement associated with multiple microcysts (Figs.
1A and
1B). The left side parotid
gland enhanced slightly more than the right side after gadolinium injection.
Fine-needle aspiration performed several months later revealed mononuclear and
inflammatory cells, and a diagnosis of chronic parotiditis was made. The
patient was given antispasmodics and broad-spectrum antibiotics to little
effect.
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Fig. 1A. —67-year-old man with painless, slowly progressive left
parotid gland mass. Unenhanced spin-echo T1-weighted axial MR image (TR/TE,
640/10) shows intermediate signal intensity and swelling of left parotid
gland. Right parotid gland is homogenous and relatively brighter.
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Fig. 1B. —67-year-old man with painless, slowly progressive left
parotid gland mass. Unenhanced fast spin-echo T2-weighted axial MR image
(5400/70) with fat saturation reveals small foci of high signal intensity
(arrows) that may represent focal dilatation of salivary ducts or
cysts.
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Fifteen months later, because the parotid gland was still swollen, helical
CT was performed. Unenhanced slices revealed a significant swelling of the
superficial lobe of the left parotid gland and multiple calcifications
disseminated throughout the gland (Fig.
1C). A slight tissue enhancement was noted in the left parotid
gland compared with the right side after IV contrast medium injection. No
focal tumoral process was clearly delineated. Sonographic examination of the
parotid gland showed a diffuse swelling of the left side and a hypoechoic
heterogeneous signal of the entire gland. Numerous foci of calcifications were
also seen.
The left parotid gland was resected. The pathologic specimen was an
enlarged parotid gland with a lobulated appearance. On cut sections,
homogeneous firm whitish nodules were punctuated by several linear
calcifications (Fig. 1D).
Microscopically, normal salivary tissue was revealed to have been destroyed by
a dense lymphocytic infiltrate (Fig.
1E). This infiltrate appeared heterogeneous with a mixture of
small lymphocytes, centrocyte-like monocytoid cells, and rare isolated blastic
cells. All these cells were immunohistochemically of B-cell origin. The
neoplastic infiltrate was located in the marginal zone around reactive B
follicles, and lymphoepithelial lesions were found, which are the hallmarks of
extra-nodal marginal zone B-cell lymphoma of MALT
[2]. Irregular calcifications
were seen at the center of some salivary ducts
(Fig. 1E).
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Fig. 1D. —67-year-old man with painless, slowly progressive left
parotid gland mass. Photograph of cut section of parotidectomy reveals
enlarged gland with lobulated and whitish areas. Numerous calcifications
(arrows) are identified.
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Fig. 1E. —67-year-old man with painless, slowly progressive left
parotid gland mass. Photomicrograph of histopathologic specimen shows abundant
small lymphocytic infiltrates are destroying normal architecture and creating
lymphoepithelial lesions (arrows). Reactive germinal center is
designated by arrowheads. Calcifications can be seen in salivary ducts
(asterisk). (H and E, x250)
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Discussion
A primary lymphoma arising in a major salivary gland is an unusual finding.
Primary lymphomas of the salivary glands account for 4.7% of lymphomas at all
sites [3]. The salivary glands
are usually involved secondary. MALT is a specialized component of the immune
system that protects the free surface of a variety of organs—especially
in the gastrointestinal tract, which is directly exposed to external agents.
The salivary glands do not normally contain MALT but may acquire it as a
result of an autoimmune inflammatory disorder, usually Sjögren's syndrome
[3]. Despite the increased
incidence of lymphoma in Sjögren's syndrome, most of the major salivary
gland lymphomas arise without association with this underlying disease. Our
patient had no clinical evidence of Sjögren's syndrome, and his labial
gland biopsy had negative findings.
Radiologic descriptions of MALT lymphoma affecting the parotid gland in
adults are scarce. A retrospective review reported the sonographic and CT
appearance of MALT lymphoma of the parotid gland in 10 HIV-infected children
[1]. The authors found that
most of those patients had multiple hypoechoic solid nodules, which correspond
to hyperplastic lymphoid tissue or lymphoma. Cystic lesions may coexist that
correspond to lymphoepithelial cysts arising from compression of terminal
parotid ducts by contiguous hyperplastic or neoplastic lymphoid tissue.
Punctuate calcification, both intracystic and parenchymal, may be present and
may result from end-stage inflammatory lesions. This radiologic appearance has
also been described in benign lymphoepithelial lesions encountered in patients
with AIDS [4] or Sjögren's
syndrome [5].
In our patient, the first MR examination showed unilateral swelling of the
parotid gland associated with multiple microcysts. No obvious calcification
was seen. This appearance was nonspecific in a healthy adult. A diagnosis of
parotiditis was retained after the results of the fine-needle aspiration
cytology. CT performed 1 year later (9 years after symptoms first appeared)
revealed that the swelling of the parotid gland persisted, and multiple
calcifications were seen. The differential diagnosis of multiple intraparotid
calcifications at this stage should include sialolithiasis, tuberculosis,
salivary calcinosis, cystic fibrosis, epidermoid metaplasia, mucoepidermoid
tumor, and osteochondroma [6,
7].
In the study by Suchy and Wolf
[8] of patients with localized
MALT lymphoma, the treatment of choice was field radiotherapy if the disease
extended to local lymph nodes or surgery if the disease was extranodal only.
Patients with disseminated lymphoma were usually treated with
chemotherapy.
MALT lymphoma is known to be associated with a high rate of response to
local treatment or chemotherapy, which results in an extended disease-free
interval and long-term survival. Our patient had isolated surgical treatment,
and no local or regional recurrence was seen after an 8-month follow-up.
To the best of our knowledge, this case is the first reported radiographic
description of unilateral MALT lymphoma of the parotid gland in an
immunocompetent adult.
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