C. Allison 1, S. Huilgol1,2
Benign cellular fibrous histiocytoma (CFH) is a variant of fibrous histiocytoma (FH), first described by Calonje et al in 1994 (1, 2). Classically, histology of CFH demonstrates high cellularity, limited polymorphism, a fascicular growth pattern with a partly storiform pattern and limited, lace- like pattern of fat infiltration (3–6). CFH comprise 5% of dermal fibrous histiocytomas (3, 5). Clinically, CFH can be frequently confused with dermatofibrosarcoma protuber- ans (DFSP). The differentiation of these tumours therefore requires histological examination plus immunohistochemi- cal staining. Despite being described as benign, 26% of CFHs recur, with rare cases reported of pulmonary and lymph node metastases (7–10). We present an educational case of CFH in a healthy 28-year-old man initially mas- querading as DFSP clinically and unable to rule out histo- logically; highlighting the importance of recognition of this rare tumour. On subsequent wide local excision, the histo- logical analysis of the tumour showed increased cellular- ity, spindle-shaped calls with a fascicular and storiform growth pattern and CD34 positivity on immunochemistry. We present the key clinicopathological features to distin- guish DFSP and CFH and a literature review on these rare CFH tumours.
References
1. Calonje E, Mentzel T, Fletcher CD: Cellular benign fibrous histi- ocytoma. Clinicopathological analysis of 74 cases of a distinctive variant of cutaneous fibrous histiocytoma with frequent recur- rence. Am J Surg Pathol 1994;18:668–676
2. Calonje E, Fletcher CD. Cutaneous fibrohistiocytic tumors: an update. Adv Anat Pathol 1994; 1: 2–15.
3. Billings SD, Patel RM, Buehler D. Soft tissue tumours of the skin. Springer-Verlag New York, 2019
4. Elder D (ed): Lever’s Histopathology of the Skin, ed 9. Philadel- phia, Lippincott Williams and Wilkins, 2005
5. Hornick JL. Practical Soft Tissue Pathology, a diagnostic approach, ed 2. Elsevier Saunders, 2018
6. Zhong YP, Wang J: Cellular fibrous histiocytoma: a clinicopatho- logic analysis and 27 cases. Chinese J of Pathol 2013;42:153–7.
7. De Hertogh G, Bergmans G, Molderez C, Sciot R. Cutaneous cel- lular fibrous histiocytoma metastasizing to the lungs. Histopathology 2002; 41: 85–-.6
8. Colome-Grimmer MI, Evans HL. Metastasizing cellular der- matofibroma. A report of two cases. Am J Surg Pathol 1996; 20:
1361–7.
9. Doyle LA, Fletcher CD: Metastasizing ‘benign’ cutaneous fibrous histiocytoma: a clinicopathologic analysis of 16 cases. Am J Surg Pathol 2013;37:484–495.
10. Nemoto D, Nishii T, Kanno K, Inui K, Masuda M. Pulmonary metastasis of cellular benign fibrous histiocytoma: A case report. J Japanese Assoc Chest Surg 2018;32:141–6.