September 2015 Case of the Month

65 year-old man with a soft tissue mass of the right neck, status post surgical excision.

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4x

Low power view shows a somewhat hypocellular spindle cell and collagenous lesion with few interspersed adipocytes. Some cords of thick, ropey collagen are noted at the left side of the field.

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10x
10x

Thick eosinophilic bands of collagen course haphazardly throughout the lesion.

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SMA
SMA

Negative

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4x

Low power view shows a somewhat hypocellular spindle cell and collagenous lesion with few interspersed adipocytes. Some cords of thick, ropey collagen are noted at the left side of the field.

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September 2015 Case of the Month

   Answer: Spindle Cell Lipoma

The excisional biopsy shows a well-circumscribed spindle cell lesion, primarily made up of three components including thick ropey collagen bundles, few scattered adipocytes, and a bland spindle cell population.  The multinucleated "floret-like" cells characteristic of pleomorphic lipoma are not observed in this case.  Notably, the lesion shows diffuse positivity for CD34 immunostain, and negativity for S-100, SMA, and desmin (not shown).  Clinically, spindle cell lipomas typically arise between the 4th and 5th decades with a striking male predominance of roughly 10:1.  The lesion most often occurs in the posterior aspect of the neck or upper back.  Spindle cell lipoma is benign and excision is curative.