Fibro-osseous pseudotumor of the digit is an unusual cutaneous process characterized histologically by a fibroblastic proliferation admixed with reactive/metaplastic osteoid formation. The osteoid formation can be florid and immature, mimicking the appearance of malignant osteoid-forming neoplasms. Fibro-osseous pseudotumor of the digit has histologic and clinical features in common with myositis ossificans. This has led many to consider the two to be synonymous. We studied three cases of fibro-osseous pseudotumor, compared to five cases of myositis ossificans, using routine light microscopy and a battery of immunohistochemical stains. Both entities displayed a "zoning" pattern of immature spindled areas admixed with more mature areas having osteoid metaplasia. This was more pronounced in myositis ossificans. In each lesion, the spindle cells stained positively for vimentin and actin. CD34 and Factor VIII highlighted the vasculature. No stromal staining for MAK-6 (cytokeratin) or S-100 was identified. Ki-67, a proliferation marker, showed positive staining of the stromal cells in both lesions, which was strongest in the immature spindled areas. The immunohistochemical and histologic similarities of the lesions support fibro-osseous pseudotumor of the digit being a cutaneous variant of myositis ossificans.

Ten keratoacanthomas with both proliferative and regressive histologic features along with 10 well‐differentiated squamous cell carcinomas were examined using immunohistochemistry for the expression of bcl‐2, a protooncogene recently recognized to be involved in protecting cells from undergoing apoptosis. The squamous cell carcinomas had a modest but diffuse staining pattern, while the proliferative keratoacanthomas stained only at the basal cells and only rare cells stained positively in the regressive keratoacanthomas. The degree and pattern of staining suggest a loss of bcl‐2 expression with tumor maturity in keratoacanthoma and a possible role in their ultimate involution. Sleater JP, Beers BB, Stephens CA, Hendricks JB. Keratoacanthoma: A deficient squamous cell carcinoma? Study of bcl‐2 expression.

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Following uncomplicated cataract surgery, a patient receiving etanercept for psoriatic arthritis developed Mycobacterium chelonae endophthalmitis. Vitrectomy, capsulectomy, and intraocular lens removal was followed by intravitreal amikacin, topical gatifloxacin, intravenous imipenem, and oral clarithromycin for six months. The patient achieved a final corrected visual acuity of 20/20. Etanercept has been implicated in the development of numerous, severe granulomatous infections, though not previously with M. chelonae. This represents the first reported case of visual recovery following M. chelonae endophthalmitis.