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Case Reports
. 2022 Sep 19;14(9):e29324.
doi: 10.7759/cureus.29324. eCollection 2022 Sep.

Collision Tumor Comprised of Atypical Fibroxanthoma and Invasive Squamous Cell Carcinoma: A Case Report of an Extremely Rare Entity

Muhammad Tahir  1 , Kurt Knowles  1 , Thuy Phung  1 , Leila A Cruthirds  1 , Spencer J Liles  2
Affiliations
Case Reports

Collision Tumor Comprised of Atypical Fibroxanthoma and Invasive Squamous Cell Carcinoma: A Case Report of an Extremely Rare Entity

Muhammad Tahir et al. Cureus. .

Abstract

Single benign or neoplastic dermal lesions are very common. Lesions with two distinct tumors occurring as a single entity are extraordinary and known as collision tumors. In the present case, the lesion was diagnosed on biopsy, and later, wide local skin excision was performed. Excision revealed that the lesion was composed of two distinct cell populations exhibiting the characteristics of two separate neoplastic entities. The histopathology revealed a single lesion comprised of moderately differentiated squamous cell carcinoma that appeared to invade an atypical fibroxanthoma. This is unprecedented in the English literature and the first such case to be reported.

Keywords: atypical fibroxanthoma (afx); collision tumor; invasive carcinoma; squamous cell carcinoma (scc); ­skin cancer.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Medium power view clearly showing nests of SCC (center) surrounded by AFX.
(4x) Magnification. SCC: squamous cell carcinoma; AFX: atypical fibroxanthoma
Figure 2
Figure 2. : Medium power view illustrating the presence of spindled to epithelioid, pleomorphic cells representing AFX and the ISCC component.
(10x) Magnification. AFX: atypical fibroxanthoma; ISCC: invasive squamous cell carcinoma
Figure 3
Figure 3. Spindle cells are arranged in irregularly sheets and fascicles with intermixed ISCC.
(20x) Magnification. ISCC: invasive squamous cell carcinoma
Figure 4
Figure 4. High power view illustrating the pleomorphic, multinucleated cells with atypical mitotic figures.
(40x) Magnification.
Figure 5
Figure 5. Immunohistochemistry showing diffuse expression of CD10 in AFX.
(4x) Magnification. AFX: atypical fibroxanthoma
Figure 6
Figure 6. Immunohistochemistry showing diffuse expression of CD68 in AFX. The areas that are not staining brown represent the SCC.
(4x) Magnification. AFX: atypical fibroxanthoma; SCC: squamous cell carcinoma
Figure 7
Figure 7. Immunohistochemistry, strong, diffuse expression of high molecular weight cytokeratin (HWMCK), CK5/CK6 in ISCC.
(4x) Magnification. ISCC: invasive squamous cell carcinoma
Figure 8
Figure 8. Dual immunohistochemistry, nuclear stain for p63 (brown) and red stain for CD10.
(4x) Magnification.
See this image and copyright information in PMC

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