Digital fibromas are common benign acral tumors typically reported as angiofibromas (AFs) or acquired digital fibrokeratomas (ADFs). Cellular variants are not well recognized.
We collected 14 acral fibrocytic lesions showing a spindle cell morphology from our files, and evaluated CD34, Factor XIIIa, epithelial membrane antigen (EMA), and S100 protein staining of these lesions. We compared the histologic and immunohistochemical features of these cellular fibromas with five digital AFs, five ADFs, and five digital dermatofibromas.
The 14 cellular digital fibromas showed intersecting fascicles of thin delicate bland spindle cells in the superficial reticular dermis with a fibrotic-to-slight myxoid stroma. The spindle cells in all cases stained strongly for CD34, and only scattered stromal cells stained for Factor XIIIa. Five tested cases were negative for EMA and S100 protein. The digital AFs, fibrokeratomas, and dermatofibromas stained predominately for Factor XIIIa, with no or minimal staining for CD34.
These findings suggest that a subset of digital fibromas is characterized by a dense cellular proliferation of CD34-positive spindle cells. Awareness of this variant of digital fibroma and its staining pattern is critical in preventing misdiagnosis as dermatofibrosarcoma protuberans, particularly in superficial biopsies.
[Show abstract][Hide abstract] ABSTRACT: Case 1: A 58-year-old man presented with a solitary asymptomatic nodule on his thumb (Figure A). After trauma with a rusty nail approximately 20 years ago, he had developed a small papule, which had enlarged gradually for a few days initially before stabilizing. His personal and family medical histories were unremarkable. Dermatologic examination revealed a 1-cm crater-like nodule on the left palmar area. This was a firm and nontender lesion that was fixed to the overlying skin but moved freely from underlying structures. There were no similar lesions elsewhere on his body. Case 2: A 52-year-old man presented with a nodular lesion on the left palmar surface of his thumb. The 0.8-cm lesion was lightly colored, with a central cup-shaped epidermal depression and thin epidermis. The patient described an insect bite to the area 15 years earlier as the precipitating event. The firm and nontender lesion was fixed to the overlying skin but moved freely from underlying structures (Figure B). Case 3: A 36-year-old man consulted for a nodular lesion, located on his left palmar surface, that had not enlarged or changed since appearing 3 years ago. He described mechanical trauma to the area as precipitating the lesion. Clinical examination revealed a 0.6-cm, well-circumscribed nodule, with a dome shape and colored skin. Clinically, the nodular lesion appeared to be a benign tumor (Figure C). In each case, the nodule was excised totally and histopathologic examination revealed a well-circumscribed, nonencapsulated nodule within the mid-dermis. Thick, acellular collagen bundles were arranged randomly in short fascicles through the center of the lesion. Cellular areas consisting of histiocytes and fibroblasts with a storiform pattern at the periphery of lesion were observed, but nuclear atypia and mitotic activity were not. Results of immunohistochemical stain with CD34 were negative, but in all cases were strongly positive for Factor XIIIa. Slight epidermal hyperplasia was present with orthokeratotic hyperkeratosis and flattened rete ridges in the overlying epidermis (Figure A-1, Figure B-1, Figure C-1). The subcutaneous fat and adjacent skin were normal. No folliculosebaceous units at the periphery of the lesion were seen, but a few eccrine sweet glands were noted. No recurrence appeared in 18 months of follow-up.
[Show abstract][Hide abstract] ABSTRACT: An overview of recent progress in silicon solar cell research at
the University of New South Wales, Australia is given. Recent results
include the demonstration of 24% cell efficiency using the passivated
emitter, rear-locally diffused (PERL) cell structure and an efficiency
approaching 18% for polycrystalline cells. An AM0 efficiency above 20%
for the former cells has been measured for the first time at NASA-Lewis,
at SERI, and at Sandia National Laboratories. Initial batches of cells
designed for concentrated sunlight have given efficiencies of up to
26.7%. In the polycrystalline cell area, an efficiency approach 18% has
been demonstrated. Recent emphasis has been on investigating innovative
approaches for texturing polycrystalline cells
Photovoltaic Specialists Conference, 1990., Conference Record of the Twenty First IEEE; 06/1990
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