Pathology

The branch of medicine dealing with the essential nature of disease, especially changes in body tissues aorgans that cause or are caused by disease. Pathology is the structural and functional manifestations of disease.

Anatomic pathology  the anatomical study of changes in the function, structure, or appearance of organs or tissues,including postmortem examinations and the study of biopsy specimens.

Cellular pathology  - Cytopathology is a diagnostic technique that examines cells from various body sites to determine the cause or the nature of disease.

Clinical pathology  pathology applied to the solution of clinical problems, especially the use of laboratory 

methods inclinical diagnosis.

Comparative pathology  that which considers human disease processes in comparison with those of other 

animals.

Oral pathology  that treating of conditions causing or resulting from morbid anatomic or functional changes in thestructures of the mouth.

Surgical pathology  the pathology of disease processes that are surgically accessible for diagnosis or treatment.

Eosinophilia:
Causes

-Allergic disorders.
-Parasitic infection.
-Skin diseases.
-Pulmonary eosinophilia.
-Myeloproliferative lesions and Hodgkin's disease.

Acanthosis nigricans is a pigmented skin lesion commonly present in the axilla which is a phenotypic marker for an insulin-receptor abnormality as well as a marker for adenocarcinoma, most commonly of gastric origin.

Erythema nodosum is the MCC of inflammation of subcutaneous fat (panniculitis).
 - it may be associated with tuberculosis, leprosy, certain drugs (sulfonamides), and is commonly a harbinger of coccidioidomycosis and sarcoidosis.
 - commonly presents on the lower extremities with exquisitely tender, raised erythematous plaques and nodules.
 - self-limited disease.

Seborrheic keratosis
1. A round, brown-colored, flat wart.
2. Most often seen in middle-aged to older adults.
3. A benign lesion.

Keratoses (Horny Growth)
1. Seborrheic keratosis is a common benign epidermal tumor composed of basaloid (basal cell-like) cells with increased pigmentation that produce a raised, pigmented, "stuck-on" appearance on the skin of middle-aged individuals.
 - they can easily be scraped from the skin's surface.
 - frequently enlarge of multiply following hormonal therapy.
 - sudden appearance of large numbers of Seborrheic keratosis is a possible indication of a malignancy of the gastrointestinal tract (Leser-Trelat sign).

 2. An actinic keratosis is a pre-malignant skin lesion induced by ultraviolet light damage.
 - sun exposed areas.
 - parakeratosis and atypia (dysplasia) of the keratinocytes.
 - solar damage to underlying elastic and collagen tissue (solar elastosis).
 - may progress to squamous carcinoma in situ (Bowen's disease) or invasive cancer.

 3. A keratoacanthoma is characterized by the rapid growth of a crateriform lesion in 3 to 6
weeks usually on the face or upper extremity.
 - it eventually regresses and involutes with scarring.
 - commonly confused with a well-differentiated squamous cell carcinoma.