Although the clinical findings of pityriasis rubra pilaris (PRP) are striking, the microscopic diagnosis can be difficult because changes can be subtle and can overlap with other skin diseases. Suprabasal acantholysis can be seen in PRP, mimicking pemphigus vulgaris. We report a patient with PRP whose initial biopsies demonstrated subcorneal acantholysis mimicking pemiphigus foliaceus.

Soft tissue chordomas (STCs) have never been systematically studied because of their rarity and the difficulty in separating them from similar-appearing lesions. Using brachyury to confirm the diagnosis, we have analyzed our experience with 11 cases. Cases coded as "chordoma" or "parachordoma" were retrieved from institutional and consultation files (1989 to 2011) and were excluded from further analysis if they arose from the bone or in a patient with previous axial chordoma. Eleven of 27 cases met inclusion criteria. Patients (8 male; 3 female) ranged in age from 13 to 71 years (mean 44 y). Tumors were located on the buttock (n=2), wrist (n=2), leg (n=2), toe (n=1), thumb (n=1), ankle (n=1), shoulder (n=1), and chest wall (n=1), ranged in size from 0.5 to 10.9 cm (mean 5.3 cm), and consisted of cords and syncytia of spindled/epithelioid cells with vacuolated eosinophilic cytoplasm and a partially myxoid background. Tumors expressed brachyury (10/10), 1 or more cytokeratins (11/11), and S100 protein (10/11). Follow-up information was available for 10 patients (69 mo; range, 2 to 212 mo). Most (n=6) were alive without disease, 2 developed local recurrence and lung metastases, and 1 developed lung metastasis only. One died with unknown disease status. STCs are histologically identical to osseous ones, but differ in their greater tendency to occur in distal locations where small size and surgical resectability result in better disease control. The existence of STC implies that notochordal remnants are not a prerequisite for chordoma development.

The interpretation of the bilateral manifestation of soft tissue sarcoma remains open, but predicts an unfavourable outcome.