fibrous papule of the nose

FIBROUS PAPULE OF THE NOSE

An increased number of cells having fibrohistiocytic features that are found in a dispersed pattern, eosinophilic collagenous stroma, abnormally coarse collagen fibers oriented perpendicular to the dermoepidermal junction, pigment incontinence, telangiectasia, and perifollicular fibrosis are characteristic of fibrous papules of the nose. The scattered fibrohistiocytic cells and the eosinophilic stroma are constant. The other features are variable from case to case and may be absent.

The cells that have the fibrohistiocytic features are mostly mononuclear, and some of these have stellate outlines. Multinucleated cells are frequently 'molded' by the adjacent collagen and are not found in the clusters characteristic of tuberculoid or sarcoidal granulomata. Similar cells may be seen in oral or lip fibromas (so-called irritation fibromas or bite fibromas). Palisading granulomata are not seen. Multinucleated cells having the features of Langerhans cells or multinucleated nevus cells may be present. True nevus cells are found in some cases, and their presence has led to the idea that fibrous papules are related to nevocellular nevi. On occasion, the fibrohistiocytic cells are cytologically atypical.

The eosinophilic collagenous stroma is best appreciated in cases where the biopsy includes adjacent basophilic solar elastotic material. It should be noted that the collagen in scars within sun damaged skin is eosinophilic. Therefore, the collagen in fibrous papules must either have been nonresponsive to sun exposure, protected from sun damage, or this collagen is re-formed collagen. The latter possibility is the most attractive. Vertical streaking of collagen, characteristically found in skin that has been picked at or secondarily lichenified, is usually present to some degree if only focally. Pigment incontinence occurs secondarily to a variety of unrelated conditions but lichenification is one of them.

Telangiectasia is so prominent in a minority of cases that a diagnosis of hemangioma is suggested. Follicular abnormalities such as perifollicular fibrosis and lesions resembling fibrofolliculomas may be present.

In view of the diversity of findings, it is tempting to speculate that fibrous papules may represent a variety of pre-existing papular lesions that have been modified by trauma such as attempts at zit popping or other trauma. However, it is more likely that the basic pathology is that of a lesion of perifollicular fibrous sheath^ref
Reed.

Multiple lesions on the face having similar histologic findings are seen in the tuberous sclerosis syndrome (adenoma sebaceum--a misnomer).

Scan view of a biopsy obtained by shaving through the base of the lesion.

Low power view. Note minimal telangiectasia.

High power view showing vertical streaking of collagen that is abnormally coarse for the collagen of the papillary dermis.

Another high power view. Stellate and multinucleated cells that are 'molded' by the stroma.

Another high power view. A cell that could be interpreted as either a nevus cell or a Langerhans giant cell containing melanin is present, and variably coarse vertical collagen bundles are seen. Multiple, dispersed mononuclear cells having fibrohistiocytic features are present.

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	Scan view of a biopsy obtained by shaving through the base of the lesion.
	Low power view. Note minimal telangiectasia.
	High power view showing vertical streaking of collagen that is abnormally coarse for the collagen of the papillary dermis.
	Another high power view. Stellate and multinucleated cells that are 'molded' by the stroma.
	Another high power view. A cell that could be interpreted as either a nevus cell or a Langerhans giant cell containing melanin is present, and variably coarse vertical collagen bundles are seen. Multiple, dispersed mononuclear cells having fibrohistiocytic features are present.