Solitary cutaneous focal mucinosis L98.5

Cutaneous focal mucinosis was first described by Johnson and Helwig in 1966 (Johnson and Helwig, 1966). In 2004, Chen et al. referred to the disease as solitary soft fibroma-like polypoid mucinosis. In 2016, it was recommended to refer to these lesions as "solitary cutaneous focal mucinosis" to distinguish it from "multiple cutaneous focal mucinosis," which may be associated with systemic disease (Kuo KL et al. 2017).

Cutaneous focal mucinosis is a rare, "pseudotumorous" papular or even nodular skin disease characterized by localized (inflammatory or degenerative) deposits of mucin, a hyaluronic acid complex in the dermis.

The lesion typically presents as an isolated, asymptomatic, unspectacular papule on the extremities or back and in most cases proves to be an incidental hsitologic finding. It is not associated with systemic disease.

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Unclear; unlike multiple cutaneous focal mucinosis, this is a localized skin disease not associated with "mucinosis-associated systemic disease." Traumatic cutaneous focal mucinosis is known (Kempf W et al. 2014; Verma G et al. 2018).

Adults aged 29 to 60

V.a. extremities, with arms more commonly affected than legs. Lesions on the head, neck, and trunk have been described.

Characteristic is an asymptomatic flesh-colored, whitish but also red papule, usually smooth on the surface.

Unlike multiple cutaneous focal mucinosis, solitary lesions are usually not associated with systemic disease; therefore, no further laboratory testing is required in these individuals (Cohen PR et al 2020).

The predominant pathologic feature of cutaneous focal mucinosis is unencapsulated mucin, a hyaluronic acid complex, in the upper dermis. It can be visualized as mild basophilic staining in sections stained with hematoxylin and eosin (HE). Although the diagnosis can be made on sections stained with HE, stains that detect mucin (such as alcian blue, colloidal iron, and toluidine blue) can be helpful in confirming the diagnosis.

Excision; recurrences are not observed.

Cutaneous focal mucinosis can occur as a solitary skin lesion (solitary cutaneous focal mucinosis). However, it also occurs as a multiple variant (multiple cutaneous focal mucinosis), but in these cases it is usually associated with systemic disease (Kuo KL et al. 2017).

The oral counterpart of cutaneous solitary focal mucinosis is called oral (solitary) focal mucinosis.

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