December 2016 - Presented by Dr. Nima Amini

Clinical History

A 75-year-old man presented with a 2 year history of a lesion on the left temple. A shave excision was performed on a 1.1 cm well-demarcated, ulcerated, brown pigmented plaque.


Microscopic Description

Microscopically, sections showed a nodular dermal proliferation of atypical spindle cells without infiltrative growth or subcutaneous involvement (Figure 1). The tumor cells were

Negative:  S100, Melan A, AE1/AE3, Desmin and CD34.  
Positive:    CD10 (strong, Figure 3) and  smooth muscle actin (SMA) (focal).

More than two years later, he presented with a left neck mass. A fine needle aspiration biopsy was performed on the secondary lesion. It showed an identical morphology and immunophenotype as the skin tumor (in addition, 34BE12, MNF116 and p63 were all negative), consistent with metastasis. (Figures 4,5,6).

Click to enlarge image

Figure 1
The well-demarcated, ulcerated primary lesion on H&E stain (20x)

Figure 2
Bizarre multinucleated tumor cells in hypercellular stroma with frequent mitotic figures, on H&E stain (200x)

Figure 2

Figure 3
Primary lesion, tumor cells are strongly positive for CD10 (200x)

Figure 3

Figure 4
Identical histologic features seen in the secondary lesion on H&E stain (200x)

Figure 4

Figure 5
Secondary lesion, tumor cells are strongly positive for CD10 (200x)

Figure 5

Figure 6
Tumor cells in secondary lesion are negative for MNF116 (200x)

Figure 6

What is the diagnosis?

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The correct answer is

B. Atypical fibroxanthoma

> Learn more about this diagnosis.