Tieger, Marisa G.; Jakobiec, Frederick A.; Ma, Lina; Wolkow, Natalie
Purpose: A case of a small benign storiform fibrous tumor of the conjunctival substantia propria is described to clarify the category of fibrous histiocytoma. In addition, a comparison of the various spindle cell tumors of the conjunctival substantia propria is explored.
Methods: The patient underwent a complete tumor excision, and the specimen was analyzed by histopathologic and immunohistochemical investigations.
Results: A cellular mass, composed solely of spindle cells in a storiform pattern without a component of histiocytic cells, was found beneath an undisturbed nonkeratinizing squamous epithelium and was separated from the epithelium by a grenz zone of uninvolved collagen. The lesion was sharply demarcated but not encapsulated. The Masson trichrome stain revealed scant deposition of intercellular collagen. The reticulin stain displayed numerous and delicate wiry fibers between the tumor cells and encircling capillaries. The Alcian blue stain demonstrated faint positivity in the interstitium. Immunohistochemistry revealed positivity for vimentin, factor XIIIa, smooth muscle actin, CD10, and CD45. Negative stains were obtained for CD34, CD56, S100, desmin, and Ki67.
Conclusions: The broad term of fibrous histiocytoma should be reserved for deep fibroblastic spindle cell tumors (e.g., those of the orbit) that display an aggressive behavior. More benign superficial spindle cell tumors of the dermis are now preferentially characterized as dermatofibromas. It is suggested that equally benign epibulbar tumors should no longer be designated as fibrous histiocytomas but rather as benign storiform fibrous tumors. Tumors completely composed of polygonal histiocytoid (epithelioid) cells that are CD34+ should be excluded from the benign storiform fibrous tumor category. Positive smooth muscle actin and factor XIIIa staining in conjunction with negative staining for CD34 and desmin in the current spindled tumor cells are findings consistent with those of cutaneous dermatofibromas. Both the epibulbar and dermal spindle cell lesions have displayed an indolent and nonaggressive behavior. Microscopically they contain a high proportion of dendrocytic stellate cells that are either factor XIIIa+ or XIIIa−. Given the anatomic differences between the dermis and conjunctiva, the term dermatofibroma is inappropriate for the current tumor; instead the term benign storiform fibrous tumor has been proposed for superficial tumors of the conjunctiva.
Aliaa H. Abdelhakim, Kristen E. Dunbar, Kyle J. Godfrey, Cristina Abascal Ananza, David N. Silvers & Michael Kazim
Purpose: Dermatofibromas are common cutaneous lesions, but rarely occur in the eyelid skin. The reason for the low incidence in the palpebral skin has not been elucidated. In this study, we analyze the histopathologic features of an illustrative case of dermatofibroma and review previously published cases to determine whether eyelid dermatofibroma develops differently from the prototypical dermatofibroma.
Methods: Histopathologic analysis of a new illustrative case of eyelid dermatofibroma and retrospective review of published cases.
Results: The distinguishing features of the illustrative lesion included a rounder gross appearance, nonacanthotic epithelium, basophilic staining, cellular character, and a paucity of “collagen trapping.” These features deviated from the typical features associated with classic dermatofibroma. Review of the 11 previously published cases of eyelid dermatofibroma revealed that they were more similar in appearance to the illustrative lesion than to classic dermatofibroma.
Discussion: The rarity and histological deviations of the eyelid dermatofibroma suggest that the dermal substrate from which the lesion develops differs from that of the classic dermatofibroma. This difference may be explained microanatomically based on the fact that the dermis of the eyelid is predominantly papillary, whereas the dermis of extrapalpebral skin where dermatofibromas are more common is predominantly reticular.
Conclusions: Although related, eyelid dermatofibromas appear to be histologically distinct from classic dermatofibromas, owing to the unique dermal composition of the site of origin.
Jakobiec, Frederick A.; Zakka, Fouad R.; Tu, Yufei; Freitag, Suzanne K
A 66-year-old man developed a painless 2 mm to 3 mm recurrent nodule at the left upper eyelid margin. Excision disclosed a spindle cell lesion without frank atypia or mitotic activity growing in a twisted fascicular pattern often referred to as storiform. All the surgical margins were involved with tumor. Immunohistochemistry demonstrated that many of the constituent spindle and dendritic tumor cells were CD34−, factor XIIIa+, and CD 163+, the latter 2 being biomarkers for monocytic lineage. The lesion was diagnosed as a dermatofibroma rather than a fibrous histiocytoma, a term that should be reserved for more aggressive lesions of deeper fascial planes. Facial dermatofibromas are rarer and more likely than those of the extremities to recur and therefore deserve wider local excision at first surgery with careful and frequent clinical follow ups. Eyelid dermatofibroma has probably often been misdiagnosed as another tumor in the past. Immunohistochemistry can supply valuable biomarker criteria for diagnosis.