Tuesday 24 September 2013
sclerozing fibroma; storiform collagenoma; solitary sclerotic fibroma
Sclerotic fibroma is a rare skin neoplasm that can be seen sporadically or in association with disorders such as Cowden’s disease. Histopathologically, the lesion is a sclerotic fibroma displaying hypocellular collagen bundles with clefts.
Sclerotic fibroma is an uncommon skin tumor associated with Cowden’s disease (multiple hamartoma syndrome). Solitary sclerotic fibroma can be seen in patients without a personal or family history of Cowden’s disease. It is characterized histologically by a well-circumscribed, nonencapsulated, dermal nodule comprising hypocellular sclerotic collagen bundles with prominent clefts.
Sclerotic fibromas may occur as a solitary sporadic tumor or in multiple numbers as part of the cutaneous manifestation of Cowden’s disease, a genodermatoses that is acquired in an autosomal dominant manner. It is unclear whether sclerotic fibroma represents a hamartoma or a true fibrocystic neoplasm.
Rapini and Golitz coined the term “sclerotic fibroma” when they reported 11 cases of solitary lesions in patients without any evidence of Cowden’s disease.5 The average patient age was 40 years with a range from 7 to 62.
There was no preferential location; however, 5 of 11 lesions were located in the head and neck region. The lesion was more common in females (8 of 11). The average lesion size was 5.5mm with a range of 2 to 9mm.
Similar reports of solitary sclerotic fibroma not associated with Cowden’s disease have also been described and reported by other authors.
Clinically, the lesion usually presents as asymptomatic, flesh-colored, white, translucent, waxy papules and can occur on any location. Solitary sclerotic fibroma is a benign lesion and no treatment is usually required. The lesion can, however, be removed through a simple excision as was done in our patient.
Histopathologically, a well-circumscribed, nonencapsulated, and sharply demarcated dermal nodule comprising hyalinized thick bands of collagen is noted. The nodule is usually hypocellular or acellular. The thick collagen bundles were arranged in a whorled or plywood-like pattern with prominent clefts between collagen bundles.
Sclerotic fibroma usually stains positive for vimentin and CD34, but negative for neurofilaments, S-100, neuron-specific enolase (NSE), carcinogenic embryonic antigen (CEA), embryonic membrane antigen (EMA), high molecular weight keratin, and cytokeratin.
A factor 13a stain shows positivity for scattered dendritic cells. This can be useful in differentiating sclerotic fibroma from a dermatofibroma, which shows diffuse positivity in the entire lesion. Bodian stain is usually negative.
It has been suggested that the lesion is an actively growing fibroblastic neoplasm with abnormal regulation of type I collagen production and processing.
Fibronectin deposition within clefts, detected by immunofluorescence, has been reported.
Proliferation of spindle cells with myoid features resulting in collagen production was recently seen under ultrastructural examination.
Sclerotic fibroma, when present in multiple numbers, serves as a clue for the presence of multiple hamartoma syndrome. When present as solitary, a sclerotic fibroma lesion is benign and treatment is usually not warranted.