Reticular erythematous mucinosis - Skin
Plaque-like cutaneous mucinosis is considered by most to be synonymous; however, some feel the conditions represent a continuum, with self-descriptive nomenclature at the ends of the spectrum.
Tumid lupus is histologically identical to and has considerable overlap with REM. Clinically, the lesions lack the reticulate nature seen in REM and may arise as isolated plaques on various parts of the body. Similar to REM, tumid lupus is usually limited to the skin and most often has negative serology for lupus (positive only in a small percentage). Some therefore consider REM a variant of tumid lupus.
UV light and hormonal influences are at play. On a cellular level, a 2001study published in 1996 demonstrated an abnormal response of the dermal fibroblasts in REM to exogenous interleukin-1β. A more recent study has shown that mucin accumulation in REM may be related to factor XIIa+ and hyaluronan synthase-2+ dermal dendrocyte populations rather than dermal fibroblasts. Endothelial cell tubuloreticular inclusions have also been reported in REM lesional skin. These inclusions may also be seen in lupus plaques, in response to viral infections, and in response to high levels of interferon, suggesting possible roles or etiologic connections.
L98.5 – Mucinosis of the skin
238946004 – Reticular erythematous mucinosis
- Tumid lupus – Chronic cutaneous lupus variant with erythematous to violaceous papules, plaques, and nodules. The lesions lack the reticulate quality of REM. Tumid lupus most often arises on the face, extensor forearms, shoulders, V-neck of chest, and back. There is considerable overlap with REM as the condition is histologically identical, usually has negative serology, and is for the most part limited to the skin.
- Cutaneous lupus mucinosis – Seen only in Japanese males, it appears as flesh-colored to red papules and nodules on the chest, giving the appearance of a lumpy chest. May precede or coincide with the development of systemic lupus erythematosus, most often with renal and articular manifestations.
- Confluent and reticulated papillomatosis – Reticulate hyperpigmentation of central chest; most often seen in adolescence. Lesions may be subtly papillated yet fail to have the infiltrated look/feel of REM and are more tan-brown than red.
- Mycosis fungoides – Recent report of two cases in which mycosis fungoides clinically mimicked REM.