Inflammatory myofibroblastic tumor of the orbit: A clinico-pathological study of 25 cases

Abstract

Background: Inflammatory myofibroblastic tumor (IMT) is a rare entity characterized by the presence of myofibroblasts and inflammatory cells within a fibrous stroma, which typically occurs in children or young adults. The IMT is considered generally a benign lesion, although about 20% of cases may experience recurrence, and most rarely develop metastasis. Herein, we present the largest series of primary orbital IMT ever reported.

Patients and methods: The clinical records of 25 patients, collected between the 1995 and 2015, with biopsy-proven diagnosis of orbital IMT were retrospectively reviewed to determine demographic, clinical, radiologic and pathological features, management, and outcome.

Results: The study included 13 females and 12 male patients, age ranged from 5 to 76 years. Disease onset was in all cases unilateral (25/25), with posterior location (10/25) or extending anterior to posterior (7/25). The most common signs and symptoms were: proptosis (19/25), ptosis (18/25), diplopia (10/25), periocular swelling (9/25), pain (8/25), redness (7/25). All patients underwent to incisional biopsy which included total or subtotal tumor resection avoiding arming of the adjacent structure, followed by systemic steroid therapy (22/25) or radiotherapy (3/25). The disease recurred in 6 (24%) patients who responded to the subsequent therapy. No one developed metastasis or died because of the disease.

Conclusion: IMT is a distinct entity which may occur in the orbit primarily. It should be considered in differential diagnosis in all orbital masses, particularly with onset of acute or subcronic inflammation. Surgical biopsy associated to a partial debulcking of the tumor, avoiding to damage adjacent vital structure may contribute to improve the outcome. Steroid therapy, seems to be the suitable as first line medical therapy, although, as reported in literature, not all cases respond to this treatment regimen. Radiotherapy, may be considered as an alternative therapy. Recurrences occurred in 24% of patients and may be treated with additional surgical resection and a new course of steroid or radiotherapy. No specific pathological features which may correlate with the prognosis have been found in this series.

Fig. 1

Age distribution of our cases showing the peak in the sixth decade.

Fig. 2

Coronal CT scan showing circumscribed mass with defined margin located in the supero-temporal quadrant of the left orbit.

Fig. 3

(a) The spindle cells with fascicular arrangement. Mitotic activity was present. The nuclei were elongated with modest blunting of the tip. Plasma cells were the predominant inflammatory cell type as small aggregates among the spindle cells or more uniformly dispersed in the background (Original magnification X100. Hematoxylin and Eosin). (b) The histopathological appearance in the same case with higher magnification of the cells (Original magnification X400. Hematoxylin and Eosin).

Fig. 4

a and b Immunohistochemistry of paraffin-embedded IMT tissue using Vimentin Antibody at dilution of 1:1000 – from two different cases with strong expression of vimentin by the proliferating cells (Original magnification × 400 Vimentin).

Fig. 5

Immunohistochemical staining of paraffin-embedded IMT tissue using muscle actin antibody- dilution of 1:500. with intense staining for α-smooth muscle actin in all of the cases, thereby indicating that the majority of the cells of the IMT are myofibroblasts (Original magnification × 400 SMA).

Fig. 6

Immunohistochemistry of the spindle tumor cells showing expression to Desmin, thus supporting our diagnosis (Original magnification × 400Desmin).

Fig. 7

Focal weaker expression of the spindle tumor cells to cytokeratin (Original magnification × 40 CytoK).