Sir,

Although adipose tissue comprises a large portion of the orbit, liposarcomas consisted of only 2% of primary orbital tumours, and were hardly ever included in the clinical differential diagnosis of orbital lesions.1

We report a 24-year-old woman who suffered from recurrent orbital liposarcoma with unusual findings. She first presented with right 3 mm exophthalmos and limitation of eye movements that developed within 2 weeks. Her visual acuity was 6/6. CT scan and MRI revealed an extraconal lesion, consisting of fat, soft tissue, and calcifications at the roof of the right orbit, pushing down the superior rectus. The patient postponed surgery for 5 months and the proptosis progressed to 6 mm. She underwent anterior and lateral orbitotomy with incomplete debulking of the tumour found between the levator and the superior rectus muscles. After surgery, she felt well for 8 months, when proptosis recurred (Figure 1a) with complete limitation of upward gaze. The visual acuity was 6/6. CT and MRI revealed a heterogenic tissue filling the right upper orbit (Figure 1b). Another operation was performed 16 months after the first one and the tumour was excised through a lid-crease incision, using a cryo-probe. At follow-up 1.5 years later, ptosis and hypoglobus persisted, but with no signs of tumour recurrence.

Figure 1
figure 1

(a) Recurrent orbital liposarcoma causes fullness of the right upper eyelid, ptosis, and hypoglobus. (b) CT scans of the recurring tumour. Heterogenic tissue fills the right orbit at the upper retrobulbar space. (c) A focus of metaplastic bone was seen in the primary lipoma-like liposarcoma (asterisk) (H&E; original magnification × 40). (d) Formations of reactive lymphoid follicles (arrows) in the relapsing, inflammatory WDL (H&E; original magnification, × 40). (The images were digitally processed.)

Full size image

Paraffin sections from the primary tumour revealed a lipoma-like well-differentiated liposarcoma (WDL) composed of adipose lobules of mature adipocytes with variations in cell size and occasional cells with hyperchromatic nuclei, and scattered bizarre, multinucleated cells. Scattered lipoblasts were identified within fibrotic septa. A focus of metaplastic bone was present (Figure 1c). The relapsing lesion was an inflammatory WDL with lipoma-like and sclerosing areas. It contained a prominent chronic inflammatory component with the formation of reactive lymphoid follicles (Figure 1d). The lipomatous component contained adipocytes varying in size, with focally hyperchromatic nuclei and scattered multivacuolar cells. The sclerosing component was paucicellular with spindle fibroblastic cells and occasional atypical cells with hyperchromatic nuclei. Immunohistochemical examination showed that the lipocytes, some of the lipoblast-like cells and some of the spindle cells were positive for S-100 protein and negative for alpha smooth muscle actin, desmin, and CD68. Immunostaining for CD3, CD20, CD68, and CD138 demonstrated a reactive immunoarchitecture of the lymphoid component.

Comparative genomic hybridization (CGH) analysis that was performed, as far as we are aware, for the first time for an orbital liposarcoma, detected same chromosomal aberrations in both the primary and relapsing tumors. Changes in the DNA sequence copy number were: +1p34−q32, +2p21−q33, +4q22−q28, +5p13−q31, +6q14−23, +8q, +12q12−q22, +13q12−q22 and −Xq. All aberrations were of a low level.

Discussion

While rare, the prognosis of orbital liposarcomas is not known. WDL outside the retroperitoneum is usually cured by wide resection with a 20–30% risk of local recurrence and up to 5% risk of dedifferentiation and metastasis.2, 3

CGH might help indicate more malignant phenotypes.4, 5, 6 While gains within chromosomes 1,4,5,6,8, 12, and 13 were found in WDL, gains within chromosomes 2 have not been reported before. Loss of chromosomal material, such as the loss of Xq found in our case, is generally detected less frequently in sarcomas than gains.4 It was suggested that an increased number of aberrations, over-representations of chromosomal subregion 12q24, and amplification of 1q may indicate a more malignant phenotype.4, 6

The commonly accepted classification of liposarcoma by the World Health Organization7 distinguishes between well-differentiated, myxoid, round cell, pleomorphic, and dedifferentiated groups. WDL is further classified into lipoma-like, sclerosing, and inflammatory subgroups.3, 7 Unusually, metaplasia into cartilaginous, osseous, and smooth muscle elements may present in liposarcoma.8 However, metaplastic bone in orbital liposarcoma, to the best of our knowledge, has not been previously described. Inflammatory WDL is rare and almost always retroperitoneal. Inflammatory WDL, as found in the recurrent lesion of our patient, has been described only once as an orbital primary tumour3 and has not been previously reported as a recurrent orbital liposarcoma.

A recent classification from The Armed Forces Institute of Pathology8 groups together the WDL, atypical lipoma, and pleomorphic lipoma into one category of ‘atypical lipomatous tumor’ located between the benign and malignant groups, as it contains cells with irregular, hyperchromatic nuclei but does not metastasize. It was also argued that the differentiation between lipoma-like, sclerosing, and inflammatory subgroups have no significance and may occur in the same tumour. Our finding of the same chromosomal imbalances in the primary lipoma-like tumour and in the inflammatory relapsing tumour also suggests that these subtypes should be grouped together.

In summary, liposarcoma with metaplastic bone and recurrent liposarcoma with inflammatory component should be added to the differential diagnosis of rare orbital lesions.