Sarcomatoid hepatocellular carcinoma with mixed osteoclast-like giant cells and chondroid differentiation

Large multinucleated giant cells having 10-25 small nuclei within the cytoplasm (osteoclast-like giant cells, D) were reactive for CD68 (H) [(A), (B), (C), (D) Hematoxylin-Eosin stain, original magnification ×200 (A), (B), (C), ×400 (D), (E), (F), (G), (H)] Immunohistochemical staining revealed that the HCC component was reactive for pan-cytokeratin (Fig. 2E) but not for AFP, antihepatocyte antigen, glypican-3. The spindle cell components revealed a positive reaction for vimentin (Fig. 2F) but not cytokeratin (Fig. 2G) and no positive reaction for desmin, smooth muscle actin, CD34, or C-kit, suggesting no specific cellular differentiation. DISCUSSION The sarcomatoid variant of carcinoma is rare but can be observed in any organs in which carcinomas can occur, such as the lung, breast, prostate, skin, gastrointestinal tract, and female genital organs.2 Terminology for these tumors are various among organs, including sarcomatoid carcinoma, spindle cell carcinoma, metaplastic carcinoma, pleomorphic carcinoma, and carcinosarcoma. The prognosis of the sarcomatoid variant of HCC is unfavorable compared with classical HCC, and there are no effective diagnostic tools except for tissue confirmation; thus, several studies have recommended close follow-up and biopsy for tissue confirmation when unusual or atypical features are found in radiological studies.3,13,14 This case was histologically typical but interesting in that it had two distinct tumor cell types on macro- and microscopic findings with a transitional zone and spindle cell