Correspondence

250 CAN J OPHTHALMOL—VOL. 43, NO. 2, 2008

Low-grade, aggressive fibrous histiocytoma of themedial canthus

Fibrous histiocytoma (FH) encompasses a heteroge-neous group of mesenchymal tumours composed of

varying proportions of fibroblastic and histiocytic ele-ments. Here we describe the rare occurrence of FH in themedial canthus.

A 26-year-old woman presented with a 5-month historyof an enlarging, mildly tender, yellowish mass in the leftmedial canthal area (Fig. 1A). Clinically, the appearancewas consistent with a noninflamed, cystic lesion, and adiagnosis of epidermal inclusion cyst was favored.Excisional biopsy revealed spindle cells occasionally in astoriform arrangement (Fig. 1B), focal vacuolated histio-cytes, rare multinucleated giant cells, and prominentperipheral sclerotic collagen bundles. There was no overly-ing epidermis or capsule. These findings were in keepingwith a benign fibrosing process. Six months later, thepatient presented with a recurrent mass requiring a secondbiopsy. This specimen had similar features but, addition-

ally, showed a hyperplastic epidermis and 3–4 atypicalmitoses in 20 high-power fields. Immunohistochemicalstaining was positive for smooth-muscle actin, muscle-spe-cific actin, vimentin, and CD68. Staining for CD34,desmin, S-100, and HMB45 was negative. The diagnosiswas low-grade aggressive FH of the medial canthus. Therehas been no further recurrence after 46 months.

FH, believed to be derived from a pluripotential primi-tive mesenchymal cell, has been described in the orbit,eyelids, conjunctiva, episclera, limbus, cornea, and lacrimalsac. In a review of 150 cases of orbital FH, Font andHidayat1 distinguished 3 groups: benign, locally aggressive,and malignant. Epithelioid and cellular variants of benignFH have been reported in the medial canthus.2 Four casesof canthal malignant FH have also been reported togetherwith a review of the differential diagnosis.3 The major dif-ferential diagnosis of benign or aggressive FH in the canthalregion is nodular fasciitis. Histologic and immunohisto-chemical findings, as demonstrated in our case, can behelpful in diagnosis; however, many overlapping featurescan make this distinction difficult. Some nodular fasciitislesions show a storiform pattern, and the amount ofmyxoid matrix can be minimal.4 Transitional forms canmake the distinction between FH and nodular fasciitis par-ticularly difficult, if not impossible in some cases.4

REFERENCES

1. Font RL, Hidayat AA. Fibrous histiocytoma of the orbit: a clini-copathologic study of 150 cases. Hum Pathol 1982;13:199–209.

2. Morris SR, DeSousa J, Barrett AW, Malhotra R. Benign fibroushistiocytoma of the eyelid mimicking keratoacanthoma.Ophthal Plast Reconstr Surg 2007;23:73–5.

3. Khong JJ, Chen CS, James CL, et al. Malignant fibrous histio-cytoma of the eyelid: differential diagnosis and management.Ophthal Plast Reconstr Surg 2005;21:103–8.

4. Weiss SW, Goldblum JR. Benign fibrous tissue tumors. In:Weiss SW, Goldblum JR, eds. Enzinger and Weiss’s Soft TissueTumors. 4th ed. St. Louis, Mo.: Mosby; 2001:247–64.

Michel J. Belliveau, Seymour Brownstein, David R. Jordan, Hamidreza Faraji

University of Ottawa Eye Institute and The Ottawa Hospital, Ottawa, Ont.

Correspondence to Seymour Brownstein, MD: sbrownstein@ohri.ca

Can J Ophthalmol 2008;43:250doi:10.3129/i08-024

Fig. 1—(A) left medial canthal lesion with a non-inflamed, cystic appearance. (B) Storiformpattern of fibroblasts characteristic of fibroushistiocytoma (hematoxylin and eosin, originalmagnification ×200). Left inset: multinucleatedgiant cell (hematoxylin and eosin, original magni-fication ×630); right inset: atypical mitosis (hema-toxylin and eosin, original magnification ×630).

Choroidal melanoma in association with juxtapapil-lary melanocytoma

A70-year-old Saudi man presented with a 4-monthhistory of reduced vision in his left eye. On exami-

nation, his vision in that eye was counting fingers near theface. The left fundus showed an elevated, dark brown,round 4 mm choroidal mass, partially overlying the optic

disc inferotemporally. The ultrasound showed moderateinternal reflectivity and sound attenuation of a vascularmass. The findings were suggestive of melanoma.

The histopathology of the enucleated globe showed adarkly pigmented peripapillary choroidal tumor with over-lying retinal detachment and subretinal fluid. Bleached sec-tions showed 2 types of cells: round-to-oval cells with abun-dant cytoplasm, pigment granules, and small nuclei,