To protect the rights of the author(s) and publisher we inform you that this PDF is an uncorrected proof for internal business use only by the author(s), editor(s), reviewer(s), Elsevier and typesetter Toppan Best-set. It is not allowed to publish this proof online or in print. This proof copy is the copyright property of the publisher and is confidential until formal publication. These proofs may contain color(colour) figures. Those figures may print black and white in the final printed book if a color(colour) print product has not been planned. The color(colour) figures will appear in color(colour) in all electronic versions of this book. s0060 MULTINUCLEATE CELL ANGIOHISTIOCYTOMA s0065 Definition • Fibroblast-like and histiocyte-like mononuclear cells u0390 p0300 • A distinctive benign dermal proliferation composed • Thickened collagen bundles, frequently hyalinized u0395 of thin-walled capillaries and veins, admixed with • Occasional inflammatory cells, predominantly u0400 scattered multinucleated cells lymphocytes • Hemorrhage absent, no hemosiderin deposition u0405 s0070 Clinical features • Decreased elastic fibers in the dermis can be observed u0410 s0075 Epidemiology • Overlying epidermis normal, but can also be u0415 p0310 • Female predominance (F:M = 3 : 1) hyperplastic u0275 • Middle-aged adult patients • Proliferation restricted to upper and middermis u0420 s0080 Presentation Immunopathology/special stains s0100 p0325 • Slowly growing single or multiple firm, red-brown to • Multinucleated cells display variable CD68 positivity p0485 violaceous papules • Vascular markers delineate endothelial cells u0430 u0285 • Multiple lesions usually distributed over the same area, occasionally bilateral Main differential diagnoses s0105 u0290 • Surface is usually smooth, occasionally scaly • Atrophic dermatofibroma p0500 u0295 • Size less than 1 cm in diameter • Microvenular hemangioma u0440 u0300 • Most common over distal extremities, particularly • Angiofibroma u0445 dorsum of hands, wrists, thighs, and legs, with less • Kaposi sarcoma u0450 frequent involvement of the face and trunk u0305 • Mucosal sites distinctly uncommon (oral cavity) u0310 • Usually symptomatic, pruritic lesions rare u0315 • Clinical variants u0320 • Linear u0325 • Eruptive u0330 • Plaquelike u0335 • Disseminated/generalized s0085 Prognosis and treatment p0390 • Spontaneous regression possible, but rare u0345 • Association with mycosis fungoides, diabetes mellitus, or vitiligo most likely coincidental s0090 Pathology s0095 Histology p0405 • Vascular proliferation, composed predominantly of thin-walled capillaries and veins u0355 • Lumina dilated or narrow u0360 • Lined by a single layer of bland endothelial cells u0365 • Each vessel surrounded by layer of pericytes f0030 u0370 • Scattered multinucleated cells Fig. 1. Multinucleate cell angiohistiocytoma. Acral skin with u0375 • Bizarre shaped a slight increase in the number of blood vessels, mild dermal u0380 • Hyperchromatic nuclei fibrosis, and scattered multunicleated giant cells. Note also mild u0385 • Angulated cytoplasm perivascular inflammatory cell infiltrate. 184 ISBN: 978-1-4557-2501-4; PII: B978-1-4557-2501-4.00003-5; Author: Calonje & Lazar & Luzar; 00003 Chapter 3.indd 184 6/12/2018 5:05:33 PM To protect the rights of the author(s) and publisher we inform you that this PDF is an uncorrected proof for internal business use only by the author(s), editor(s), reviewer(s), Elsevier and typesetter Toppan Best-set. It is not allowed to publish this proof online or in print. This proof copy is the copyright property of the publisher and is confidential until formal publication. These proofs may contain color(colour) figures. Those figures may print black and white in the final printed book if a color(colour) print product has not been planned. The color(colour) figures will appear in color(colour) in all electronic versions of this book. Multinucleate Cell Angiohistiocytoma 185 Fig. 2. Multinucleate cell angiohistiocytoma. Another area featuring distinctive multinucleated giant cells in the dermis, proliferation of f0035 small blood vessels, mild fibrosis, and perivascular inflammation. f0040 Fig. 3. Multinucleate cell angiohistiocytoma—higher magnification. ISBN: 978-1-4557-2501-4; PII: B978-1-4557-2501-4.00003-5; Author: Calonje & Lazar & Luzar; 00003 Chapter 3.indd 185 6/12/2018 5:05:36 PM To protect the rights of the author(s) and publisher we inform you that this PDF is an uncorrected proof for internal business use only by the author(s), editor(s), reviewer(s), Elsevier and typesetter Toppan Best-set. It is not allowed to publish this proof online or in print. This proof copy is the copyright property of the publisher and is confidential until formal publication. These proofs may contain color(colour) figures. Those figures may print black and white in the final printed book if a color(colour) print product has not been planned. The color(colour) figures will appear in color(colour) in all electronic versions of this book. s0110 BENIGN FIBROUS HISTIOCYTOMA (DERMATOFIBROMA) s0115 Definition especially over the tips of rete ridges (so-called dirty p0525 • One of the most common benign soft tissue fingers) proliferations in the skin • Proliferation of immature hair-follicle structures u0560 u0460 • Neoplastic process is favored over a reactive above the dermal proliferation is frequently seen condition due to the absence of spontaneous and can mimic a basal cell carcinoma or an adnexal regression, tendency for local recurrence(s), extremely tumor rare locoregional and distant metastases, as well as • Papillary dermis is usually, but not always, spared u0565 the recent detection of fusions in protein kinase C (so-called grenz zone) and membrane-associated proteins in some fibrous • Defining histological features include u0570 histiocytomas • Spindle cells growing in a haphazard, vague, u0575 u0465 • Represents a group of morphologically diverse storiform or short intersecting fascicular pattern proliferations with different clinical presentations and • Histiocytes in variable proportions, including u0580 biological potential multinucleated giant cells (touton and foreign body type), siderophages, and foamy cells s0120 Clinical features • Inflammatory cells in variable proportions, usually u0585 s0125 Epidemiology lymphocytes p0545 • Broad age distribution, most common in middle-aged • Delicate collagenous or loosely myxoid stroma u0590 adults containing thin-walled blood vessels u0475 • Slight female predominance • Ill-defined nonencapsulated proliferation in the u0595 dermis/superficial subcutis s0130 Presentation • Growth into subcutis usually in the form of short u0600 p0560 • Virtually any site of skin can be affected extensions u0485 • Most commonly on the limbs (about 70%), followed • Individual bundles of collagen surrounded by u0605 by the trunk lesional cells, so-called collagen trapping, especially u0490 • Slowly growing, firm solitary nodule, round to oval at the periphery of the lesion u0495 • Overlying skin often reddish-brown to darkly • Lesions restricted to subcutis or deeper structures rare u0610 pigmented and scaly • Several histological variants have been recognized, u0615 u0500 • Size of the lesion is usually less than 10 mm including cellular, epithelioid, aneurysmal, atypical u0505 • Central dimple formation on lateral compression or (pseudosarcomatoid), lipidized (“ankle type”), squeezing is a common clinical sign clear cell, palisading, deep, signet sing cell, fibrous 1 u0510 • History of previous trauma occasionally present histiocytoma with osteoclast-like cells, cholesterolotic u0515 • Clinical variants • Different variants can coexist within a single lesion u0620 u0520 • Giant variant, including plaquelike, measuring from 35 to 300 mm Immunopathology/special stains s0150 u0525 • Eruptive variant, usually related to • Although factor XIIIa is usually positive, it may p0720 immunosuppression, HIV infection, and highly just delineate a background population of dermal active antiretroviral therapy dendrocytes • See variants for additional immunohistochemical u0630 s0135 Prognosis and treatment features p0615 • Simple excision is curative u0535 • Recurrences after incomplete or marginal excision Molecular genetic features s0155 have been estimated to develop in less than 2% of • Gene fusions involving multiple protein kinase p0735 cases. C–encoding genes (PRKCA, PRKCB, or PRKCD) with a u0540 • Lesions occurring on the face and certain variety of other genes have been documented morphological variants (cellular, aneurysmal, • The prevalence and distribution of these fusions in u0640 atypical) are associated with a higher recurrence rate the various subtypes of benign fibrous histiocytoma (up to 26%) are not known, but they are only present in a subset. u0545 • Rare metastases have been reported in particular variants of fibrous histiocytoma (cellular, aneurysmal, Main differential diagnoses s0160 atypical); however, no histological features have been • Nodular fasciitis p0750 detected to predict metastatic potential • Dermatofibrosarcoma protuberans u0650 • Scar u0655 s0140 Pathology • Xanthoma u0660 s0145 Histology • Xanthogranuloma u0665 p0640 • Epidermis above the lesion is usually hyperplastic • Melanocytic lesions u0670 u0555 • Elongation and broadening of rete ridges associated with hyperpigmentation of basal keratinocytes 186 ISBN: 978-1-4557-2501-4; PII: B978-1-4557-2501-4.00003-5; Author: Calonje & Lazar & Luzar; 00003 Chapter 3.indd 186 6/12/2018 5:05:36 PM