Keloidal and other collagen patterns in atypical fibroxanthomas

Area of Science:

• Dermatopathology
• Oncology
• Histology

Background:

• Collagen deposition in cutaneous neoplasms has variable origins, including host response or tumor cell production.
• Desmoplastic variants of neoplasms are recognized, but intratumoral collagen in atypical fibroxanthoma (AFX) is considered uncommon.
• The presence of keloidal collagen in AFX is noted, yet poorly documented in existing literature.

Observation:

• A review of 91 atypical fibroxanthoma (AFX) cases diagnosed between 1999 and 2008 was conducted.
• The majority of AFX cases (92%) occurred on the head or neck in patients with a mean age of 75.
• Prominent intratumoral keloidal collagen was identified in 19% of the reviewed AFX cases.

Findings:

• The study identified prominent intratumoral keloidal collagen in a significant subset (19%) of atypical fibroxanthoma (AFX) cases.
• This observation contrasts with the conventional understanding that intratumoral collagen is rare in AFX, except for the sclerotic subtype.
• The pleomorphic subtype of AFX was the most frequently encountered (67%).

Implications:

• The presence of keloidal collagen in AFX raises questions about its origin: host response versus tumor cell product.
• This finding may offer insights into the controversial histogenesis of AFX and suggest a possible involutional stage or favorable prognosis.
• The study advocates for recognizing this keloidal collagen variant within AFX subtypes to improve diagnostic accuracy and guide future research.