Clinical Definition
A cyst is a pathological, closed cavity or sac that is distinct from the surrounding tissue, typically lined by epithelium (true cyst) or connective tissue (pseudocyst). These structures may contain fluid, gas, or semi-solid material (such as keratin or cellular debris). While predominantly benign, cysts can manifest in almost any anatomical structure, ranging from cutaneous epidermal inclusion cysts to visceral lesions in the kidneys, liver, or ovaries.
Clinical Coding & Classification
| System / Category | Code(s) | Description |
|---|---|---|
| ICD-10-CM | L72.0 | Epidermal cyst (Sebaceous cyst) |
| ICD-10-CM | N83.2 | Other and unspecified ovarian cysts |
| ICD-10-CM | Q61.3 | Polycystic kidney, unspecified (Congenital) |
| CPT (Surgical) | 11400 – 11446 | Excision, benign lesion including margins (e.g., cutaneous cyst) |
| CPT (Surgical) | 10060 – 10061 | Incision and drainage of abscess (often used if cyst is infected) |
Epidemiology & Statistics
Cysts are ubiquitous in clinical practice, affecting all age groups and demographics. Epidermoid cysts are the most common cutaneous cysts, occurring approximately twice as frequently in men as in women. Visceral cysts, such as simple renal cysts, increase in prevalence with age; it is estimated that 50% of individuals over the age of 50 possess at least one renal cyst. Polycystic Ovarian Syndrome (PCOS), characterized by multiple ovarian cysts, affects approximately 6-12% of women of reproductive age.
Pathophysiology (Mechanism)
The pathogenesis of cyst formation varies by etiology but generally follows three main mechanisms:
1. Duct Obstruction: Blockage of a drainage duct leads to the accumulation of secretions. For example, obstruction of the pilosebaceous follicle leads to the retention of keratin and sebum, forming an epidermoid cyst.
2. Epithelial Sequestration: During embryonic development, epidermal cells may become trapped within deeper tissues, proliferating to form congenital cysts (e.g., Dermoid cysts).
3. Hormonal Stimulation: In conditions like PCOS, hormonal dysregulation prevents the normal maturation and release of follicles, resulting in multiple cystic structures.
Standard Management Protocols
Management is dictated by the cyst’s location, size, and symptomatology. Asymptomatic cysts are generally observed (“watchful waiting”).
- Surgical/Procedural Interventions:
- Complete Excision: The definitive treatment for cutaneous cysts involves the surgical removal of the entire cyst wall (capsule). Incomplete removal of the capsule often leads to recurrence.
- Incision and Drainage (I&D): Indicated primarily for inflamed or infected cysts (abscesses) to relieve pressure and purulence, though recurrence is common if the sac remains.
- Fine Needle Aspiration: Used for diagnostic purposes or to drain fluid-filled cysts (e.g., breast cysts or ganglions), though re-accumulation of fluid is possible.
- Pharmacological Classes:
- Antibiotics: Indicated only when secondary bacterial infection is present (e.g., cellulitis surrounding a ruptured cyst).
- Intralesional Corticosteroids: Occasionally used to reduce inflammation in non-infected, inflamed cysts.
Healthcare Resource Utilization
While cutaneous cysts utilize minimal resources (outpatient minor procedures), visceral cysts can drive significant healthcare costs due to:
- Diagnostic Imaging: Requirement for Ultrasound, CT, or MRI to differentiate simple benign cysts from complex or malignant cystic neoplasms (e.g., Bosniak classification for renal cysts).
- Surgical Pathology: Histopathological examination is routine for excised lesions to rule out malignancy.
