Reticular erythematous mucinosis: histopathological and immunohistochemical features of 25 patients compared with 25 cases of lupus erythematosus tumidus

Reticular Erythematous Mucinosis in an African Woman with HIV Infection: Case Report and Literature Review

Reticular erythematous mucinosis is a rare and persistent form of primary idiopathic mucinosis, often referred to as plaque-like cutaneous mucinosis or midline mucinosis. It presents with reticulate patches or erythematous plaques with predilection for the anterior and posterior trunk. Affected patients are frequently asymptomatic. Pruritus or burning sensations were reported after exposure to the sun. The aetiology remains obscure; its pathogenesis is poorly understood, particularly in immunocompromised patients such as HIV-infected patients. The disease associations are not uniformly documented. Antimalarial agents significantly improve and shorten the course of the disease. We report a case of a 31-year-old African woman with underlying HIV infection who displayed the classical clinical and histological features of reticular erythematous mucinosis. This condition is rare among the HIV-infected patients, particularly in those of African descent, in whom lichen myxoedematosus/scleromyxoedema variants and acral persistent papular mucinoses were most frequently reported. The higher incidence of photosensitivity in HIV-infected individuals including the patients with skin of colour may play a potential role in reticular erythematous mucinosis. Its relationship with lupus erythematosus and photosensitivity in the context of HIV infection is discussed. To the best of our knowledge, this is the first reported case of reticular erythematous mucinosis in an African HIV-infected patient. This case highlights the need for diagnostic awareness in cases presenting with erythematous plaques and patches in a net-like pattern developing on the midline and sun-exposed areas of the trunk.

Lupus Erythematosus Tumidus: Clinical and Pathological Features in a Series of 20 Patients

OBJECTIVE

We sought to assess the clinicopathologic/immunophenotypical features in patients with lupus erythematosus tumidus (LET).

METHODS

All skin biopsies diagnosed as LET in 16 years were retrieved from our pathology laboratory. Clinical charts were reviewed and immunohistochemical markers were performed. Subpopulations of cells in the infiltrates were studied, as well as the number/distribution of plasmacytoid dendritic cells (PDC), which were compared with two control groups: normal skin and discoid lupus erythematosus. Direct immunofluorescence was performed when available.

RESULTS

We found 20 patients (11 men and 9 women; mean age 43.5 years); the mean evolution previous to diagnosis was 20.3 months. They all had erythematous, nonscarring urticarial-like plaques: 8 in the head region only, 8 in trunk/limbs only; both segments were affected in 2 patients; topography was unknown in 2. Except for 1 patient, no one developed systemic lupus erythematosus. A dense perivascular/periadnexal superficial-to-deep lymphocytic infiltrate and stromal mucin deposition were characterized histopathologically; interphase changes were absent. Immunophenotype supported an inflammatory profile. The differential count of CD123 + PDC in 10/20 cases of LET (n = 1180) was notably higher than 5 cases of discoid lupus erythematosus (n = 419) and 5 cases of normal skin (n = 38). No immune deposits were found in 2 cases.

CONCLUSION

LET is a rare, peculiar form of cutaneous lupus erythematosus that only exceptionally evolves to systemic lupus erythematosus . Its clinical-pathologic/immunophenotypical features are very characteristic. The amount of CD123 + PDC is a very helpful feature among the criteria for its diagnosis and seems to be relevant in its pathogenesis.

Primary Cutaneous CD4-Positive Small/Medium T-Cell Lymphoproliferative Disorder Mimicking Jessner Lymphocytic Infiltrate and Tumid Lupus-A Report of Two Cases

ABSTRACT

Primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder is a benign lymphoproliferative disorder composed of small-sized to medium-sized pleomorphic cells expressing a follicular helper T-cell phenotype. Jessner lymphocytic infiltrate and tumid lupus are cutaneous conditions characterized by the presence of rich dermal lymphocytic infiltrates with a superficial, deep, perivascular and periadnexal distribution that include copious amounts of dermal mucin deposition. We report 2 cases of primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder presenting with markedly increased dermal mucin, mimicking both Jessner lymphocytic infiltrate and tumid lupus and provide a review of the differential diagnosis and highlight key distinguishing features.

Reticular Erythematous Mucinosis: Exclusive Involvement of the Axillary Region

Reticular erythematous mucinosis is a primary cutaneous mucinosis characterized by the presence of erythematous macules, papules, or plaques coalescing into a reticular pattern that typically involves the midline of the chest or back in middle-aged women. Because of this peculiar location, it is also called midline mucinosis. Although atypical disease localizations have been described in the literature, these have always been accompanied by midline involvement. We report a case of reticular erythematous mucinosis with exclusive involvement of the axillary region.

Comparative Analyses of Clinical Features, Histopathology, and CD123 Immunohistochemistry of Oral Lupus Erythematosus, Lichen Planus, and Other Lichenoid Lesions

BACKGROUND

Oral lupus erythematosus (OLE) and oral lichen planus (OLP) are among the common causes of oral lichenoid lesions (OLLs). The differential diagnosis among causes of OLLs, particularly between OLE and OLP, is challenging as they have significant clinical and histopathological overlap.

OBJECTIVES

To compare and summarize the clinical, histopathological, and direct immunofluorescence (DIF) findings between OLE, OLP, and other OLLs and to explore the diagnostic value of CD123 immunohistochemistry.

METHODS

A retrospective study on patients with OLE, OLP, and other OLLs was performed between January 2014 and December 2019. The baseline characteristics, the clinical, histopathological, and DIF features, as well as CD123 immunohistochemistry for plasmacytoid dendritic cells (PDCs) were statistically analyzed and compared between groups.

RESULTS

Of 70 patients, 12 had OLE, 39 had OLP, and 19 had other OLLs. Oral erosions/ulcers were the most common findings in all three groups. Red macules, telangiectases, and discoid plaques were more common in OLE patients, while OLP cases were typified by reticulated patches (p < 0.05). Additionally, white patches were found more often in other OLLs than in both OLE and OLP (p = 0.002). Histologically, mucosal atrophy, basal vacuolization, and perivascular infiltrate were observed in OLE, whereas OLP specimens possessed mucosal hyperplasia, hypergranulosis, and compact orthokeratosis (p < 0.05). Mucosal spongiosis was a histologic feature that favored other OLLs over OLE and OLP (p < 0.001). Data on DIF were nonspecific for all three conditions. For immunohistochemical staining, the median number of total CD123+ PDCs was observed to be higher in OLE than OLP in the mucosal-submucosal junction (MSJ) (p = 0.021), the superficial perivascular area (p = 0.026), and the superficial and deep perivascular areas (p = 0.001). Likewise, PDCs in clusters ≥2+ were seen in significantly higher numbers on OLE than OLP along the MSJ (p = 0.002), the superficial perivascular area (p < 0.001), as well as the superficial and deep perivascular areas (p = 0.011). CD123+ PDCs were found to be significantly more numerous in both OLE and OLP than other OLLs in all of the abovementioned areas (all p < 0.05).

CONCLUSION

While there are some differences in the clinicopathological features between OLE, OLP, as well as other OLLs, a significant overlap remains. The quantity and distribution pattern of CD123 immunohistochemical staining has a diagnostic implication in differentiating OLE from OLP and other OLLs.

A case report of a localized reticular erythematous mucinosis like eruption of the lower legs mimicking cutaneous larvae migrans

Reticular erythematous mucinosis is an uncommon type of cutaneous mucinosis. Typically, reticular erythematous mucinosis affects middle-aged women and usually appears as papules and plaques on the mid-upper trunk. Histologically, biopsies of reticular erythematous mucinosis reveal increased deposition of dermal mucin and perivascular lymphocytic inflammation. Infrequently, reticular erythematous mucinosis has been reported in males and in atypical locations other than the trunk. In these instances, reticular erythematous mucinosis can present a diagnostic challenge clinically and histologically. This case describes the clinical and histologic findings of a localized variant of reticular erythematous mucinosis in a 65-year-old male patient.

Reticular erythematous mucinosis: Literature review and case report of a 24-year-old patient with systemic erythematosus lupus

Reticular erythematous mucinosis (REM) was first described 50 years ago, but only around 100 case reports in English have been published. Its relation with other inflammatory skin disorders is still being debated. We report a case of REM, including the clinical and histopathological findings. Also, a systematic review of 94 English-language reported cases is provided. The described criteria for clinical and histopathological diagnosis are highlighted in order to REM can be confidently diagnosed.

Lupus erythematosus tumidus: clinical perspectives

Lupus erythematosus tumidus (LET) is an uncommon and photosensitive inflammatory skin disorder which is characterised by erythematous urticarial plaques. In the last 20 years, extensive research on clinical and histological aspects of the disease have led to a better characterization of this nosological entity and to differentiate it from other similar or related diseases. Today, LET is considered as a separate subtype of cutaneous lupus erythematosus (CLE) with a benign, intermittent clinical course (intermittent CLE, ICLE) and only rarely associated with systemic lupus erythematosus (SLE).

An unusual clinical presentation of lupus erythematosus tumidus localized on the thigh

A 44-year-old woman with seronegative polyarthritis presented with a 2-year history of a solitary, bluish-red, oedematous, nonscaly, annular and partially reticulated macule on her right thigh. Histopathological findings revealed perivascular and periadnexal lymphocytic infiltrate in the dermis. Alcian blue and colloidal iron stains highlighted mucinous deposit in the upper and mid dermis. Direct immunofluorescence showed a linear deposit of IgG and C3 along the basement membrane zone. Antinuclear antibody was positive at a titre of 1 : 80, with homogenous and speckled patterns. Except for its unusual localization and lack of photosensitivity, our case had the clinical and histopathological features of lupus erythematosus tumidus. These characteristics were also reminiscent of reticular erythematous mucinosis and erythema annulare centrifugum, both of which are considered to be associated with cutaneous lupus erythematosus (CLE). Hydroxychloroquine 200 mg daily led to improvement of the skin lesion. The unusual clinical presentation of our case emphasizes the heterogeneity of clinical manifestations of CLE.