Mohs Surgery Report: Spindle Cell Fibrohistiocytic Tumors: Classification and Pathophysiology

Abstract

Four patients with spindle cell cutaneous fibrohistiocytic neoplasms are presented. A classification scheme for this group of tumors is discussed along with the histologic and immunohistochemical criteria needed to establish the diagnosis. Cutaneous malignant fibrous histiocytoma (atypical fibroxanthoma) may behave biologically as a neoplastic rather than reactive mesenchymal tumor with definite invasive and metastatic potential.

The Evolving Conception and Management Challenges of Malignant Fibrous Histiocytoma

“…The combined recurrence rate in all studies of MMS used to treat MFH published before 1990 is 7.4%, with an average follow‐up of 41.7 months . In contrast, the next series of MFH treated using MMS were not published until after 2000, reporting a mean recurrence rate (37.5%) considerably higher than described in the earlier studies ( p = .07) .…”

“…The combined recurrence rate in all studies of MMS used to treat MFH published before 1990 is 7.4%, with an average follow-up of 41.7 months. 8,20 In contrast, the next series of MFH treated using MMS were not published until after 2000, reporting a mean recurrence rate (37.5%) considerably higher than described in the earlier studies (p = .07). 19,21 The inclusion of our data, representing the largest contemporary cohort of MFH treated with MMS, elevates the average "modern" recurrence rate to 58.8%, which is markedly higher than the average recurrence rate described before the cytopathologic improvements of the early 1990s (p < .001), with a comparable length of follow-up, at 29.6 months ( Table 3).…”

“…In the dermatologic literature, MFH has historically been conceptualized as a deeper and more‐aggressive variant of atypical fibroxanthoma (AFX), with studies published before 1990 largely failing to distinguish between these tumors, but more‐recent research has cast some doubt on this notion because distinct molecular and immunohistochemical markers have been described for AFX and MFH . Investigators have also reported dissimilar patterns of clinical behavior, with AFX typically regarded as a low‐ to intermediate‐grade sarcoma arising almost exclusively in photodamaged sites and MFH characterized by a more‐variable presentation along with a high propensity for local invasion, in‐transit metastases, and systemic spread.…”

“…Mohs micrographic surgery (MMS) has occasionally been employed, with the majority of cases reported during the 1980s, before major advances in techniques for histologic diagnosis. Investigators have reported considerably lower recurrence rates than observed with WLE while achieving maximum tissue preservation, providing a particularly efficacious treatment option in the head and neck region …”

“…Investigators have reported considerably lower recurrence rates than observed with WLE while achieving maximum tissue preservation, providing a particularly efficacious treatment option in the head and neck region. 8,[19][20][21] Unfortunately, the clinical rarity and evolving histopathologic definitions of MFH have complicated attempts to compare and evaluate different treatment modalities effectively. As a tertiary referral center, our institution provided the opportunity to examine a large and contemporary cohort of these tumors.…”