Ординатура / Офтальмология / Английские материалы / Diagnostic Atlas of Common Eyelid Diseases_Dutton, Gayre, Proia_2007
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Figure 1 A lesion of the epithelium with loss of epithelial surface characteristics of fine wrinkles and cellular structure.
Figure 2 Dermal lesions displace the epithelium upward usually without obliterating fine surface features.
The dermis also contains epithelial appendages which are the source for many eyelid lesions. The pilosebaceous unit consists of the hair follicle and associated holocrine sebaceous gland and apocrine sweat gland of Moll. All of these structures can be the site of origin for eyelid lesions. The diverse cellular components of this apparatus can give rise to many different lesions that can look similar clinically. Lesions are grouped into four major categories depending upon differentiation towards sebaceous, hair follicle, apocrine, or eccrine tissues. Within these groups lesions are further subdivided into hyperplasias, hamartomas, adenomas, and carcinomas.
The hair follicle is a tubule with root cells at the base around the papilla and bulb (Fig. 3). Higher up follicular epithelium lines the follicle, and finally cortical cells lay down the outer keratin layers to the hair. Tumors arising from proliferations of cortical cells are termed pilomatrixomas. Solid proliferations of follicular cells manifest as trichofolliculomas, whereas an obstruction of the follicle results in a cystic lesion called a trichilemmal cyst. Solid tumors arising from the basal epithelial bulb are tichoepitheiomas.
Large sebaceous glands empty into the hair follicle. Proliferations of the secretory epithelium produce solid dermal tumors called sebaceous adenomas (Fig. 4). Occasionally the excretory
Figure 3 Hair follicle lesions. |
Figure 4 The hair follicle and associated dermal lesions. |
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Figure 5 Apocrine glands of Moll. |
Figure 6 The eccrine sweat gland can be the origin of |
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several dermal lesions. |
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duct becomes blocked with accumulation of sebum, producing a sebaceous cyst (steatocystoma). More commonly, however, the block is higher up in the follicle and although the cyst is still contains some sebum the epithelial lining adds keratin and leads to the diagnosis of trichilemmal ( tricholemmal) or pilar cyst. Apocrine sweat glands of Moll normally produce a somewhat viscous secretion that empties into the hair follicle (Fig. 5). Solid tumors arising from the secretory epithelium give rise to apocrine adenomas. If the duct becomes obstructed, a cyst results that can have a layered precipitate of cellular debris. These are apocrine hidrocystomas.
Eccrine sweat glands empty directly to the skin surface (Fig. 6). Like the apocrine sweat glands, these can form solid and cystic lesions. Benign tumors arising from the ductal epithelium are called syringomas, whereas those from the tubular secretory epithelium are nodular hidradenomas. An obstruction of the secretory duct will result in an eccrine hidrocystoma filled with a clear fluid. Clinically, the eccrine and apocrine cysts may not always be distinguishable.
Vascular elements are present in the dermis and can give rise to a number of important eyelid lesions (Fig. 7). These include hemangiomas and angiosarcomas derived from endothelial cells, and hemangiopericytomas arising from the endothelial pericyte. Arteriovenous hemangiomas or malformations are abnormal vascular channels. Nerves are another component of the dermis and are the tissues of origin for neural tumors such as neurofibromas.
Figure 7 Blood vessels and nerves in the dermis and subcutaneous tissues serve as the sites of origin for several vascular and neural lesions.
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In addition to cutaneous layers and their included adnexal appendages eyelid lesions can arise from other eyelid structures. Most important in this group are the tarsal plate meibomian glands. These are modified holocrine sebaceous glands arranged as tubules, with about 25 to 30 in the upper eyelid and 20 in the lower lid. They are not associated with the eyelashes or a pilosebaceous unit, although they can occasionally revert to such a structure where they can be related to the development of abnormal hairs called distichiasis. An obstruction of the meibomian duct can result in an infected cyst called a chalazion. In contrast, a similar infection involving small isolated sebaceous glands (glands of Zeis) or those associated with the skin pilosebaceous units results in a more acute and superficial process called a hordeolum. Any of these sebaceous glands can also give rise to a malignant tumor, the sebaceous cell carcinoma.
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Chapter 5
Histopathologic Terminology
The use of descriptive terms in histopathology is a valuable method for standard communication which allows both the pathologist and the clinician to understand specific histologic characteristics of biological materials. One or more of these characteristics may be specific for certain lesions, thus allowing a more precise diagnosis. In some cases, knowledge of such characteristics can also help the clinician make a provisional diagnosis that might allow therapeutic decisions such as to biopsy or not, or to treat medically or to observe.
In the following pages we describe and illustrate the more common descriptive terms in histopathologic diagnosis, which are used throughout this book.
Acantholysis
Acantholysis is the loss of cohesion between epidermal (or epithelial) cells leading to the formation of intraepidermal clefts, vesicles, or bullae. Primary acantholysis results from dissolution or separation of the desmosomes between unaltered cells. Secondary acantholysis occurs between damaged cells such as during viral infection. An example of primary acantholysis in pemphigus vulgaris is shown.
Acanthosis
Acanthosis is an increase in the thickness of the squamous cell layer (stratum spinosum) of the epidermis. Acanthosis often results in elongated projections of the epidermis into the dermis, as shown in this example.
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Actinic Elastosis
Actinic elastosis, also referred to as solar elastosis, is characterized by lightly basophilic, irregular, thickened elastic fibers in the dermis. Individual fibers are sometimes not evident, and there may be only an amorphous mass of lightly basophilic material in the dermis. Elastic tissue stains may be used to highlight actinic elastosis.
Apoptosis
Apoptosis is programmed cell death recognizable morphologically by chromatin condensation, cell shrinkage, and hypereosinophilia. Apoptotic cells with no remaining nucleus appear as homogenous, eosinophilic, round structures termed colloid bodies or cytoid bodies. Apoptosis requires energy, transcription of new genes, and protein synthesis.
Ballooning Degeneration of the Epidermis
In ballooning degeneration of the epidermis, marked intracellular edema leads to acantholysis and subsequent formation of an intraepidermal vesicle or bulla. Ballooning degeneration is characteristic of cutaneous viral infections.
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Birefringence
Birefringence is the splitting of a light wave into two waves that have perpendicular polarizations and speed of travel. Birefringence results from a substance having different indexes of refraction, and is thus also referred to as double refraction. Birefringent objects appear as shining bodies on a dark background when viewed with polarized light. Birefringent objects are usually white or yellow in sections stained with hematoxylin and eosin. Collagen and hair are normal structures in the skin that are birefringent, while foreign bodies are the
most frequent extraneous birefringent materials. Amyloid is birefringent when stained with Congo red, as shown here.
Bulla
A bulla is a fluid-filled blister greater than 0.5 or 1 cm in diameter, depending on the author. Bullae may be subcorneal (shown), intraepidermal, suprabasilar, or subepidermal.
Colloid Body
Colloid bodies are also known as cytoid bodies, Civatte bodies, hyalin bodies, and apoptotic bodies. They are apoptotic epidermal cells (keratinocytes) lacking nuclei and appear as homogeneous, eosinophilic, and round structures. Colloid bodies are not specific for any disease, but they are commonly seen in lupus erythematosus, lichen planus, and graft-versus-host disease.
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Decapitation Secretion
Decapitation secretion is characteristic of apocrine cells. During decapitation secretion, portions of the apical eosinophilic cytoplasm of the cells is pinched off into the lumina lined by the apocrine cells.
Dyskeratosis
The meaning of the term dyskeratosis varies depending on the disease. In acute graft-versus-host disease, lichen planus, and lupus erythematosus, dyskeratotic cells are cells undergoing apoptosis and are smaller than adjacent epidermal keratinocytes, have brightly eosinophilic cytoplasm, and shrunken hyper-basophilic nuclei (see Apoptosis). In acantholytic dermatosis, the dyskeratotic cells are also termed “corps ronds” and have a central, basophilic, pyknotic nucleus surrounded by a clear halo and enveloped within a basophilic or eosinophilic rim. Neoplastic dyskeratosis is manifest as brightly eosinophilic bodies, sometimes with remnants of
nuclei, within a tumor (shown). These bodies represent neoplastic cells undergoing apoptosis.
Epidermotropism
Epidermotropism is the presence of atypical lymphocytes in the epidermis without spongiosis and is characteristic of mycosis fungoides. The atypical lymphocytes in the epidermis may occur singly surrounded by a clear halo or they may form small clusters referred to as Pautrier microabscesses.
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Epithelioid Cells
Epithelioid cells are activated macrophages that have an epithelial-like appearance. They are large cells with oval to elongated nuclei, eosinophilic cytoplasm, and indistinct cell borders. They occur singly or may form groups termed granulomas.
Exocytosis
Exocytosis refers to the presence of inflammatory cells within the epidermis in conjunction with spongiosis. Exocytosis is characteristic of inflammatory dermatoses.
Fibrinoid Degeneration (Necrosis)
Fibrinoid degeneration, also referred to as fibrinoid necrosis, is manifest by the deposition of fibrin within vessel walls or dermal collagen. Fibrin is homogeneous and eosinophilic in sections stained with hematoxylin and eosin. In the skin, fibrinoid necrosis of vessel walls is seen in leukocytoclastic vasculitis, while fibrin deposition in dermal collagen is seen in rheumatoid nodules and sometimes in lupus erythematosus, especially the systemic variant. An orbital vessel in a patient with Wegener’s granulomatosis is shown.
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Foam Cell
A foam cell is a macrophage laden with lipid, causing it to have vacuolated, bubbly-appearing cytoplasm.
Foreign Body Giant Cell
A foreign body giant cell is a multinucleated giant cell derived from fusion of epithelioid cells (activated macrophages). Foreign body giant cells are characterized by their large size and haphazardly arrayed nuclei.
Granulation Tissue
Granulation tissue is the hallmark of wound healing, and the term comes from the soft, pink, granular appearance when viewed from the surface of a wound. Histologically, granulation tissue consists of a proliferation of small blood vessels and fibroblasts, often accompanied by edema.
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Granuloma
A granuloma is a microscopic aggregate containing varying proportions of activated macrophages (epithelioid cells), multinucleated giant cells resulting from fusion of epithelioid cells, and other mononuclear leukocytes (lymphocytes, plasma cells, monocytes, and macrophages). Foreign body granulomas are reactions to relatively inert particles and typically have multinucleated giant cells, macrophages, and usually only small numbers of epithelioid cells. Immune or allergic granulomas are a response to insoluble particles that can induce a cell-mediated immune response; they may result from foreign substances such as zirconium,
beryllium, or dyes used for tattoos, or microbes such as Mycobacterium tuberculosis and fungi. Immune/allergic granulomas typically contain abundant epithelioid cells and variable numbers of multinucleated giant cells. Other descriptors used for granulomas are sarcoidal, tuberculoid, and palisading. Sarcoidal granulomas, also termed naked granulomas, have epithelioid cells and multinucleated giant cells with only a sparse periphery of lymphocytes (shown). Sarcoidal granulomas are characteristic not only of sarcoidosis, but they also are seen in some infections, granulomatous rosacea, orofacial granulomatosis (including the MelkerssonRosenthal syndrome), and as a response to some foreign materials. Tuberculoid granulomas have epithelioid cells, multinucleated giant cells (especially Langhans’ giant cells), and a moderate to dense periphery of lymphocytes. Central necrosis (“caseation necrosis”) may or may not be present. Tuberculoid granulomas are characteristic not only of Mycobacterium tuberculosis infection but are also seen in other infectious diseases. Palisading granulomas in the skin have a central zone of degenerated collagen (termed “necrobiosis”) surrounded by macrophages, palisading epithelioid cells, lymphocytes, and variable numbers of multinucleated giant cells. Palisading granulomas are characteristic of granuloma annulare, necrobiosis lipoidica, rheumatoid nodules, and necrobiotic xanthogranuloma.
Horn Cyst
A horn cyst is a circumscribed, round, intraepidermal accumulation of keratin. Keratin-filled invaginations of the epidermis are referred to as “pseudo-horn cysts.” Both horn cysts and pseudo-horn cysts are characteristic of seborrheic keratoses, though they may also be seen in other neoplasms of the skin.
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