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Spindle cell lipoma and
pleomorphic lipoma occur in adults and are more common in males.
These are located on the back of the neck, upper back or shoulders.
These tumours usually present as a solitary, painless, slow growing,
lobular mass with an average diameter of 5 cms. Rarely multiple lesions
may develop. Cut surface has a yellow or grayish - yellow colour.
Sometimes mucoid areas are present.
Histological features of Spindle
cell lipoma:
This is a well circumscribed lesion usually confined to the subcutis.
Some lesions are confined to the dermis (intradermal spindle cell lipoma).
The tumour consists of an admixture of adipocytes and spindle cells.
Spindle cells are arranged in short fascicles.
The spindle cells are small and elongated and contain bland, uniform
nuclei and pale eosinophilic cytoplasm.
In areas nuclear palisading is present.
The stroma is characterized by the presence of eosinophilic collagen
fibres.
Numerous mast cells are present. There is no increase in mitoses.
Some cases show prominent myxoid changes.
The adipocytes are mature.
No lipoblasts are seen.
In 'pseudoangiomatous variant' , irregular branching vascular channel
together with villiform connective tissue projections are present.
Pseudoangiomatous
spindle cell lipoma with "true" angiomatous features.Virchows
Arch. 2005
Oct;447(4):781-3. Epub 2005 Oct 19.
Histological features of Pleomorphic lipoma :
Image
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This is a well circumscribed
tumour which is usually superficial in location.
The tumour consists of mature adipocytes, abundant interstitial collagen,
together with bizarre, often multinucleated cells (floret giant cells).
Some lipoblast like cells are also present. Mitoses is usually absent.
There is minimal adipocytic nuclear atypia.
In spindle cell lipoma immunohistochemistry reveals CD34 , vimentin and
XIIIa positive stromal cells.
Spindle cell lipoma and pleomorphic lipoma share common karyotypic
abnormalities - Rearrangements of 13q and 16q.
Differential diagnosis of
spindle cell lipoma and pleomorphic lipoma:
Differential diagnosis of spindle cell lipoma -
Schwannoma
and
neurofibroma
(Adipocytes absent, S100 protein positive ).
In
well differentiated liposarcoma
(atypical lipoma)-sclerosing variant
careful clinicopathological
correlation is important . Unlike pleomorphic lipoma these are usually
located in deeper tissue .There is variation in size of adipocytes
together with other atypical features. Scattered lipoblasts are also
present.
Differential diagnosis of pleomorphic lipoma also includes
pleomorphic liposarcoma.
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IMAGE LINKS:(Spindle cell lipoma): Click1
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