Papular mucinosis affects adults of both sexes equally and appears between ages 30 and 80. Recently, it has been reported in patients infected with the HIV/AIDS virus.

Papular mucinosis (also known as "Scleromyxedema," "Generalized lichen myxedematosus," and "Sclerodermoid lichen myxedematosus") is a rare skin disease. Localized and disseminated cases are called papular mucinosis or lichen myxedematosus while generalized, confluent papular forms with sclerosis are called scleromyxedema. Frequently, all three forms are regarded as papular mucinosis. However, some authors restrict it to only mild cases. Another form, acral persistent papular mucinosis is regarded as a separate entity.

Verrucous lupus erythematosus (also known as "Hypertrophic lupus erythematosus") presents with non-pruritic papulonodular lesions on the arms and hands, resembling keratoacanthoma or hypertropic lichen planus.

The cause of prurigo nodularis is unknown, although other conditions may induce PN. PN has been linked to Becker's nevus, linear IgA disease, an autoimmune condition, liver disease and T cells. Systemic pruritus has been linked to cholestasis, thyroid disease, polycythaemia rubra vera, uraemia, Hodgkins disease, HIV and other immunodeficiency diseases. Internal malignancies, liver failure, renal failure, and psychiatric illnesses have been considered to induce PN, although more recent research has refuted a psychiatric cause for PN. Patients report an ongoing battle to distinguish themselves from those with psychiatric disorders such as delusions of parasitosis and other psychiatric conditions.

In 2016, interferon gamma/CXCL10 axis was hypothesized to be a target for treatments that reverse inflammation. Apremilast is undergoing investigation as a potential treatment .

Prurigo nodularis (PN), also known as nodular prurigo, is a skin disease characterised by pruritic (itchy) nodules which usually appear on the arms or legs. Patients often present with multiple excoriated lesions caused by scratching. PN is also known as Hyde prurigo nodularis, "Picker's nodules", atypical nodular form of neurodermatitis circumscripta, lichen corneus obtusus.

Lichen simplex chronicus is a distinct clinical entity.

In contrast to cutaneous LP, which is self limited, lichen planus lesions in the mouth may persist for many years, and tend to be difficult to treat, with relapses being common. Atrophic/erosive lichen planus is associated with a small risk of cancerous transformation, and so people with OLP tend to be monitored closely over time to detect any potential change early. Sometimes OLP can become secondarily infected with Candida organisms.

Sarcoidosis involves the skin in about 25% of patients. The most common lesions are erythema nodosum, plaques, maculopapular eruptions, subcutaneous nodules, and lupus pernio. Treatment is not required, since the lesions usually resolve spontaneously in two to four weeks. Although it may be disfiguring, cutaneous sarcoidosis rarely causes major problems.

As PNP is ultimately caused by the presence of a tumor, it is not contagious. There is no known way to predict who will become afflicted with it. Patients with cancer are therefore a group at risk. Although PNP has been known to affect all age groups, it is more likely to afflict middle-aged to older patients.

Subcutaneous sarcoidosis (also known as "Darier–Roussy disease" and "Darier-Roussy sarcoid") is a cutaneous condition characterized by numerous 0.5- to 0.3-cm deep-seated nodules on the trunk and extremities.

Scar sarcoid (also known as "Sarcoidosis in scars") is a cutaneous condition characterized by infiltration and elevation of tattoos and old flat scars due to sarcoidosis.

Mucosal sarcoidosis is a cutaneous condition characterized by pinhead-sized papules that may be grouped and fused together to form a flat plaque.

Erythrodermic sarcoidosis is a cutaneous condition and very rare form of sarcoidosis.

Lichen sclerosus may have a genetic component. Higher rates of lichen sclerosus have been reported among twins and among family members.

The disease can last for a considerably long time. Occasionally, "spontaneous cure" may ensue, particularly in young girls.

Lichen sclerosus is associated with a higher risk of cancer. Skin that has been scarred as a result of lichen sclerosus is more likely to develop skin cancer. Women with lichen sclerosus may develop vulvar carcinoma. Lichen sclerosus is associated with 3–7% of all cases of vulvar squamous cell carcinoma. In women, it has been reported that 33.6 times higher vulvar cancer risk is associated with LS. A study in men reported that "The reported incidence of penile carcinoma in patients with BXO is 2.6–5.8%".

Granuloma annulare in HIV disease is a skin condition characterized typically by papular and generalized skin lesions.

Nodular lichen myxedematosus is a cutaneous condition characterized by multiple nodules on the limbs and trunk, with a mild or absent papular component.

Discrete papular lichen myxedematosus is a skin condition caused by fibroblasts producing abnormally large amounts of mucopolysaccharides characterized by the occurrence of waxy, flesh-colored papules.

Generally, lichen nitidus is asymptomatic and self-limited; therefore, no treatment is required. However, if persistent pruritus is present, or the appearance “...interferes with daily activities or outlook...” topical glucocorticoids may be tried. If the disease process is symptomatic, generalized and extensive, oral glucocorticoids may be indicated. Other reported treatments include PUVA, UVA/UVB phototherapy, astemizole, acitretin, and etretinate.

When appears with sun/humidity; air conditioning (cool dry air) reduces swelling and discomfort.

If the lesions are mild, the patient will be subject to a good deal of pain. If the lesions are severe, the overall quality of life is devastating. The impaired skin barrier function commonly leads to localized infection, which sepsis and death may follow. The pain from the oral and pharyngeal ulcers interfere with eating, which can compromise nutritional health.

The general prognosis for PNP is poor. It is more hopeful if the tumor is benign, but in the case of malignant tumors, the mortality rate is roughly 90%. The two most commonly associated types of tumors are non-Hodgkin lymphoma and chronic lymphocytic lymphoma; nearly all of these patients die within two years of diagnosis. This is attributed to the effects of the tumor combined with the negative side effects of the medication administered to treat PNP.

Roughly 1/3 of the deaths from PNP stem from pulmonary insufficiency which is brought about by the action of PNP on the respiratory mucosa. It manifests as dyspnea and progresses to bronchiolitis obliterans (non-reversible obstructive lung disease) via an unknown mechanism.

Acral persistent papular mucinosis is a skin condition caused by fibroblasts producing abnormally large amounts of mucopolysaccharides, characterized by bilaterally symmetrical, flesh-colored papules localized to the hands and wrists.

Generalized granuloma annulare is a skin condition of unknown cause, tending to affect women in the fifth and sixth decades, presenting as a diffuse but symmetrical, papular or annular eruption of more than ten skin lesions, and often hundreds.

Perforating folliculitis is a skin condition in humans characterized by discrete follicular keratotic eruptions involving mainly the hairy parts of the extremities.

Lichen aureus (also known as "lichen purpuricus") is a skin condition characterized by the sudden appearance of one or several golden or rust-colored, closely packed macules or lichenoid papules.

Lichen nitidus is a chronic inflammatory disease of unknown cause characterized by 1–2 mm, discrete and uniform, shiny, flat-topped, pale flesh-colored or reddish-brown papules that may appear as hypopigmented against dark skin. Occasionally, minimal scaling is present or can be induced by rubbing the surface of the papules. The disease usually affects children and young adults and is painless and usually nonpruritic, although protracted itching may occur in some cases. It is sometimes referred to by dermatologists as "mini lichen planus".

Atypical lichen myxedematosus (also known as "Intermediate lichen myxedematosus") is a skin condition caused by fibroblasts producing abnormally large amounts of mucopolysaccharides.

Autoimmune estrogen dermatitis presents as a cyclic skin disorder, that may appear eczematous, papular, bullous, or urticarial. with pruritus typically present, skin eruptions that may be chronic but which are exacerbated premenstrually or occur immediately following menses.

A papulosquamous disorder is a condition which presents with both papules and scales, or both scaly papules and plaques.

Examples include psoriasis, lichen planus, and pityriasis rosea.