Thorough examination may lead to the detection of extraoral manifestations of LP that provide additional support for the diagnosis or the identification of clinical findings that suggest another diagnosis. Tissue biopsies of oral LP help to confirm the diagnosis and are particularly of value for erythematous and erosive LP, which share features with multiple other mucosal disorders, including oral malignancy. Biopsies to confirm oral LP are less essential in patients who present with classic reticular LP, particularly in patients in whom a diagnosis of LP has already been confirmed through biopsy of an extraoral manifestation of this disorder. Differential diagnosis
Skin
Lichenoid drug eruption
The cutaneous manifestations resemble idiopathic lichen planus. Chronic graft-versus-host disease
The history of preceding hematopoietic cell transplant is helpful for diagnosis
Psoriasis
Atopic dermatitis
Cutaneous lupus erythematosus
Discoid lupus erythematosus

Mouth
Oral lichenoid drug reaction
Lichenoid drug eruptions may be caused by a variety of systemic medications and share clinical features with oral LP. Histologic findings of a deep mixed infiltrate with lymphocytes, plasma cells, and neutrophils (with or without eosinophils) and perivascular inflammation favor this diagnosis. Oral lichenoid contact reaction (allergic contact mucositis)
Oral lichenoid contact reactions may be caused by a variety of substances. The clinical and histologic features of oral lichenoid contact reactions are similar to oral LP. Patch testing and recognition of the proximity of an offending substance to the eruption can aid with diagnosis. Autoimmune blistering diseases
Mucous membrane pemphigoid and other autoimmune blistering diseases may present with oral erosions and desquamative gingivitis similar to that seen in erosive LP.
In people either older or younger E. coli is the most common bacterial infection. Treatment involves the use of antibiotics. Fourniers gangrene
Fourniers gangrene (an aggressive and rapidly spreading infection of the perineum) usually presents with fever and intense pain. It is a rare condition but fatal if not identified and aggressively treated with a combination of surgical debridement and broad spectrum antibiotics. Others
Many other less common conditions can lead to testicular pain. These include inguinal hernias, injury, hydroceles, degenerative disease of lumbar spine, disc herniations, and varicoceles among others. Testicular cancer is usually painless. Another potential cause is epididymal hypertension (also known as "blue balls"). Diagnostic approach
Physical findings
The cremaster reflex (elevation of the testicle in response to stroking the upper inner thigh) is typically present in epididymitis but absent in testicular torsion as the testis is already elevated. Prehns sign (the relief of pain with elevation) though a classic physical exam finding has not been found to be reliable in distinguishing torsion from other causes of testicular pain such as epididymitis. Laboratory tests
Useful tests that may help in the determination of the cause include a urinalysis (usually normal in testicular torsion). Pyuria and bacteriuria (white blood cells and bacteria in the urine) in patients with acute scrotum suggests an infectious cause such as epididymitis or orchitis and specific testing for gonorrhea and chlamydia should be done. All people with chronic pain should be tested for gonorrhea and chlamydia. Imaging
Ultrasound is useful if the cause is not certain based on the above measures.