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Soft Tissue Pathology 

Pathology of Storiform Collagenoma (Sclerotic Fibroma) ; Giant Cell Collagenoma ; Pleomorphic Fibroma

Dr Sampurna Roy MD


Dermatopathology Quiz Case 166

Diagnosis: Giant Cell Collagenoma




Pathology of Storiform Collagenoma (Sclerotic fibroma)

Storiform collagenoma or sclerotic fibroma is a rare benign skin neoplasm that usually affects young and middle-aged adults.

This lesion was first described in association with Cowden's disease by Weary et 1972. 

In 1989, Rapini and Golitz described 11 cases of solitary sclerotic fibroma in the absence of Cowden's disease, suggesting the term 'solitary sclerotic fibroma' of the skin.

The terms hypocellular fibroma and circumscribed storiform collagenoma have also been used for this entity.

Site: This tumor is often found in the head and neck region, upper extremities and chest. Multiple lesions are usually located in the oral cavity.

Gross:  They are small white or flesh-colored waxy papules ranging in size from 0.5 to 1.2 cm. Multiple lesions of this type have been reported in the multiple hamartoma syndrome (Cowden's disease).

Microscopic features:

These are well-circumscribed, unencapsulated dermal nodules characterized by epidermal atrophy, a whorled appearance of sclerotic collagen bundles separated by clefts containing mucin, and sharp demarcation of the lesions from the surrounding normal skin. 

The hyaline collagen bands are virtually acellular.

Immunohistochemistry: The tumour cells express CD34, vimentin and factor XIIIa, but are negative for markers of neural or melanocytic differentiation.  In some cases alpha-smooth-muscle actin positive myofibroblasts are present.

Differential Diagnosis : Sclerotic fibroma shares a common immunoprofile with Pleomorphic Fibroma (discussed later), but is distinct from dermatofibroma (Sclerotic variant of dermatofibroma) and other common spindle cell lesions of skin.

Pacinian collagenoma: Composed of paucicellular collagen fibres arranged in concentric lamellations giving rise to an onion-skin appearance.

The cells are CD34 positive. Differential diagnosis: Perineurioma

Pleomorphic sclerotic fibroma:  In the superficial portion the tumour showed features of a pleomorphic fibroma, the deeper portion showed features of a sclerotic fibroma, and a transitional area is present in between. 

According to some authors, pleomorphic fibroma, sclerotic fibroma, and pleomorphic sclerotic fibroma form a spectrum.


Further reading:

Sporadic sclerotic fibroma of the oral soft tissues. 

Sclerotic fibroma-like change in various neoplastic and inflammatory skin lesions: is sclerotic fibroma a distinct entity?

Solitary sclerotic fibroma of skin: a possible link with pleomorphic fibroma with immunophenotypic expression for O13 (CD99) and CD34.

Ultrastructural and immunohistochemical characterization of the so-called giant multinucleate cells in cutaneous collagenomas.

Sclerotic fibroma-like dermatofibroma: an uncommon distinctive variant of dermatofibroma.

Solitary sclerotic fibroma of the skin: a sclerotic dermatofibroma?

Expression of CD34 in sclerotic ("plywood") fibromas.


Pathology of Giant Cell Collagenoma

Giant cell collagenoma was described for the first time by Rudolph et al in 1998.

It is a cutaneous fibrous neoplasm that usually affects young to middle-aged adults.

Despite its similar histological appearance with circumscribed storiform collagenoma, no association of Giant cell collagenoma with Cowden's syndrome has been described so far.

Gross: Presents as solitary slow-growing flesh-coloured nodules in young and middle-aged adults.

Microscopic feature: These lesions are characterized by sharply demarcated matrix consisting of coarse hyalinized collagen bundles arranged in a prominent storiform pattern and  separated by mucin-containing clefts. 

Admixed with the collagen matrix, there are two distinct cell populations.

(i) spindle-shaped mononuclear cells, and (ii) bizarre multinucleated giant cells.  

Atypical nuclei or mitotic figures are not present.

Immunohistochemistry:  Mononuclear cells expressed vimentin and actin HHF35. Multinucleated cells only expressed vimentin. 

The cells are negative for cytokeratin, desmin, S-100 protein, CD34, factor XIIIa, and the macrophage markers KP1, Mac 387.

Differential diagnosis: Storiform collagenoma, Pleomorphic fibroma ; Dermatofibroma ; solitary myofibroma


Further reading:

Giant cell collagenoma: case report and review of the literature.

Giant cell collagenoma: a benign dermal tumor with distinctive multinucleate cells.

Nonepithelial skin tumors with multinucleated giant cells.

Giant cell collagenoma on the palm.

Giant cell collagenoma of the bulbar conjunctiva

Solitary giant cell collagenoma


Pathology of Pleomorphic Fibroma

This lesion was described by Kamino et al in 1989.

Clinically presents as a slow-growing polypoid skin tag-like or dome shaped lesion in middle aged and elderly patients.

Site: on the trunk or extremities and rarely in head, neck, and subungual locations.

Microscopic features:

Well-circumscribed tumour composed of pleomorphic mononucleated and multinucleated cells with atypical nuclei with rare mitotic figures.

The cytologic pleomorphism is considered as a degenerative process as seen in a number of other mesenchymal tumours.

Immunohistochemistry:  CD34  positive. 

Desmin, Ki-M1p antibodies (pan-monocytic/macrophage marker) or S100 protein-Negative.

Staining for factor XIIIa has been patchy.

Differential diagnosis:

Benign tumours:  Dermatofibroma with atypical cells ; Giant cell fibroblastoma, pleomorphic lipoma ; sclerotic fibroma.

Malignant tumours: Undifferentiated pleomorphic sarcoma ; Atypical fibroxanthoma;

Limited local recurrence may occur but there have been no reports of regional extension or metastatic spread.



Further reading:

Pleomorphic fibroma of the skin: a benign neoplasm with cytologic atypia. A clinicopathologic study of eight cases.

Subungual pleomorphic  fibroma.

Pleomorphic sclerotic fibroma.

Pleomorphic fibroma of the skin, a form of sclerotic fibroma: an immunohistochemical  study. 

Pleomorphic sclerotic fibroma: a case report and literature review.  

Differential expression of CD34 and Ki-M1p in pleomorphic fibroma and dermatofibroma with monster cells.





Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)  ;  Dermpath-India  ;   Soft Tissue Tumour Online ; Cardiac Path Online ;

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