Dept. of Dermatology - University of Iowa College of Medicine

A Tutorial in Dermatologic Pathology

DermPathTutor © - DICTIONARY

by Mary Seabury Stone, M.D. and Thomas L. Ray, M.D.

N.B. - If you have questions about skin lesions or diseases, consult a dermatologist. Inquiries to this WebSite about skin disease entities will not be answered. If you seek additional information, try searching the WWW, or consult a dermatology textbook, readily available at a medical library. A medical librarian can help you find the material you seek.

Normal Skin (x2), Normal Acral Skin, Normal Oral Mucosa, and Normal Hair Follicle.

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Acantholysis -

The loss of cohesion between epidermal or adnexal keratinacytes.

Acanthosis -

The increase in the thickness of the stratum malpighii.

Anaplasia -

The atypical appearance of nuclei as is found in malignant neoplasia. Anaplastic nuclei are usually large, irregular and hyperchromatic, and may produce bizarre or atypical mitotic figures.

Antoni type A Tissue

An arrangement of Schwann cells nuclei forming palisading parallel rows that enclose a homogeneous material that is devoid of nuclei, and has scant or no collagen.

Apoptosis -

The dropping off of colloid bodies from the epidermis into the dermis. Apoptosis typically occurs in disorders in which basal cell damage occurs, such as lichenoid tissue reactions.

Ballooning Degeneration -

A cytoplasmic swelling of epidermal cells with loss of intercellular bridges as seen in viral vesicles.

Birefringence -

The property of appearing bright white in a dark field when examined with polarized light. Collagen, hair and silica are some of the more common birefringent materials.

Bulla -

A cavity of at least 5 mm in diameter forming within or below the epidermis.

Caseation Necrosis -

Identical to coagulation necrosis and ischemic necrosis. The affected tissue has lost its structural outline and appears as pale eosinophilic, amorphous and finely granular. Until the necrosis is far advanced some shrunken or fragmented nuclei are present.

Civatte or Colloid Body -

Eosinophilic, round homogeneous structures seen in the epidermis or upper dermis. They form through degeneration of epidermal cells and are most commonly seen in lichenoid tissue reactions. Also see Apoptosis.

Colliquative Necrosis -

Necrosis associated with the formation of pus.

Corps Grains, Corps Ronds -

Acantholytic, dyskeratotic, basophilic cells. Corps ronds have round nuclei with a perinuclear halo. Grains have an elongeated "grain shaped" nucleus. These cells are seen in Darier's, Grover's and warty dyskeratoma.

Decapitation Secretion -

Apocrine secretion where part of the apocrine cell "pinches off" and is released into the lumen of the gland.

Dyskeratosis -

Faulty and premature keratinization of individual keratinocytes. Dyskeratotic cells are usually intensely eosinophilic and may contain a small, dense, basophilic nuclear remnant. Dyskeratotic cells may also be densely basophilic as seen in Darier's disease.

Epidermolytic Hyperkeratosis -

Also called granular degeneration. It is characterized by:

1. perinuclear clear spaces in the upper stratum malpighii
2. indistinct cellular boundaries
3. a markedly thickened granular layer with increased numbers of keratohyalin granules and
4. hyperkeratosis

Epidermotropism -

The presence of mononuclear cells in the epidermis, without the presence of spongiosis. Occurs in mycosis fungoides. Not to be confused with exocytosis.

Epithelioid Cells -

Cells derived from macrophages, seen in granulomas and characterized by a large, usually oval, pale, vesicular nucleus with a clearly visible nuclear membrane. The cytoplasm is abundant, ill-defined and slightly eosinophilic.
Multinucleated epithelioid or giant cells arise from mature macrophages that fuse rather than divide. Langhans giant cells have nuclei in a semicircle at the cell periphery. Foreign body giant cells have nuclei distributed randomly.

Erosion -

An area where the epidermis is lost without dermal loss.

Exocytosis -

The presence of mononuclear cells in the epidermis with spongiosis (or microvesiculation). Occurs in inflammatory conditions. Not to be confused with epidermotropism.

Foam Cell -

A lipid-laden macrophage.

Giant Cell -

Large multinucleated cells. Epidermal multinucleated giant cells are characteristic of herpes virus infections. Histiocytic giant cells whose nuclei form a horseshoe arrangement are called Langhans type giant cells. Touton type giant cells have a ring of nuclei surrounding foamy cytoplasm with cytoplasm usually also visible around the nuclei. Foreign-body giant cells have a haphazard nuclear arrangement.

Granular Degeneration -

See Epidermolytic Hyperkeratosis.

Granulation Tissue -

Newly formed dermis arising in healing wounds and characterized by numerous fibroblasts and new capillaries and an infiltrate consisting of lymphoid cells, macrophages, and plasma cells.

Granuloma -

A chronic proliferative lesion consisting of mononuclear cells and epithelioid cells or multinucleated giant cells or both. These cells lie in groups and are often surrounded by lymphoid cells. "Naked" granulomas have few to none of these surrounding lymphoid cells.

Grenz Zone -

A narrow area of uninvolved dermis between the epidermis and a dermal inflammatory or neoplastic infiltrate. "Grenz" is German for "border".

Hyalin -

Homogenous eosinophilic material that is PAS-positive and diastase-resistant and has glycoprotein as a major component.

Hydropic degeneration of basal cells -

Also called liquefaction degeneration, it is a type of degeneration causing vacuolization of the basal cells. This process may lead to pigment incontinence. It is seen in lupus erythematosus, dermatomyositis, LS&A, ashy dermatosis and in early lichen planus.

Indian Filing -

An extension of single rows of cells between and around collagen bundles.

Karyorrhexis -

The fragmentation of nuclei, producing nuclear dust. See Leukocytoclasis and Nuclear Dust.

Keratohyalin -

The deeply basophilic, irregularly shaped granules in the stratum granulosum. These form the interfibrillary matrix which cements keratin fibrils, and the marginal band of the horny cells.

Lacuna -

A slitlike intraepidermal vesicle or bulla as is seen in Darier's disease.

Leukocytoclasis -

The disintegration of leukocytes (primarily pmn's) resulting in nuclear dust as seen in leukocytoclastic vasculitis.

Melanophage -

A macrophage that has ingested melanin.

Metachromasia -

The phenomenon of reacting with a different color from that of the dye used in staining. For example amyloid shows reddish metachromasia when stained with crystal violet.

Metaplasia -

The change of one type of tissue to another, such as metaplastic ossification seen in certain cutaneous tumors.

Microabscess -

Small collection of inflammatory cells.

• Munro microabscesses are composed of degenerated pmn's in the horny layer and are seen in psoriasis and seb derm.
• Spongiform pustules of Kagoj are multilocular pustules in the upper stratum malpighii within a sponge-like network made up of flattened keratinocytes. They are seen in psoriasis, Reiter's disease, geographic,tongue and rarely in candidiasis.
• Pautrier microabscesses are a collection of 3 or more atypical mononuclear cells within the epidermis in mycosis fungoides.

Necrobiosis -

Altered collagen that loses its normal eosinophilic coloration and fibrillar appearance, becoming slightly bluish and "smudged".

Nuclear Dust -

Fragmented nuclei scattered in the dermis, predominantly around blood vesses. Seen in vasculitis.

Papillomatosis -

Upward proliferation of epidermis and subepidermal papillae causing the surface epidermis to show irregular undulation.

Parakeratosis -

Retention of nuclei in the stratum corneum. This is a normal finding on mucous membranes.

Pigment Incontinence -

The deposition of melanin in the dermis, which when not in association with a pigmented lesion implies prior basal layer damage.

Pleomorphism -

The variation in the appearance of the nuclei of the same cell type. If pronounced and associated with large, irregular, hyperchromatic nuclei it is termed anaplasia and is often an indication of malignancy.

Polymorphism -

The variation in the types of cells, particularly used in terms of inflammatory infiltrates.

Pseudoepitheliomatous Hyperplasia -

Extreme irregular acanthosis with downward epidermal proliferation which may simulate a well differentiated squamous cell carcinoma.

Pseudohorn Cyst -

Intraepidermal keratin-filled space which due to the plane of sectioning resembles a cyst, but actually represents an epidermal invagination.

Pyknosis -

Condensation of nuclear chromatin producing a dense, shrunken appearing nucleus.

Reticular Degeneration-

A process in which severe intracellular edema results in bursting of keratinocytes and formation of multilocular bullae formed by remaining cell walls. It is seen in acute dermatitis and in viral blisters.

Spongiosis-

Intercellular epidermal edema seen as an increase in the width of spaces between cells.

Squamotization -

Replacement of the normally cuboidal or columnar basal cells with polygonal or flattened keratinocytes. This occurs mainly in lichenoid tissue reactions.

Storiform -

A pattern of cellular arrangement which is seen in certain fibrous tumors when the elongated cells intersect or intertwine at various angles so as to resemble the weaving of a doormat.

Ulcer -

An area where epidermis and part of the dermis is missing.

Verocay Body

An arrangement of Schwann cells nuclei forming palisading parallel rows that enclose a homogeneous material that is devoid of nuclei, and has scant or no collagen.

Vesicle -

A small bulla, generally less than 5 mm.

Villus -

A dermal papilla extending into a bulla, vesicle, or lacuna which is covered with a single layer of epidermal cells resulting from suprabasalar acantholysis.

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