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We report a case of autoimmune bullous disease (AIBD) with IgG and IgM autoantibodies against epidermal basement membrane zone (BMZ), which showed recurrence of mucocutaneous lesions after coronavirus disease 2019 (COVID-19) mRNA vaccination. A 20-year-old Japanese woman with a 4-year history of epidermolysis bullosa acquisita (EBA) presented to our clinic. She noticed fever and rash on the same day and visited at our hospital 2 days later. Physical examination revealed blisters, erosions and erythema on the face, shoulder, back, upper arms, and lower lip. A skin biopsy from the forehead showed subepidermal blister. Direct immunofluorescence showed linear depositions of IgG, IgM, and C3c in the epidermal BMZ. By indirect immunofluorescence of 1M NaCl-split normal human skin, circulating IgG autoantibodies were bound to the dermal side of the split at 1:40 serum dilution, and circulating IgM antibodies were bound to the epidermal side of the spilt. After the increase of prednisolone dose to 15 mg/day, the mucocutaneous lesions resolved in a week. The present case is the first case of possible EBA with IgG and IgM anti-BMZ antibodies, in which the mucocutaneous lesions were recurred after COVID-19 mRNA vaccination. Clinicians should be aware that bullous pemphigoid-like AIBDs, including EBA and IgM pemphigoid, might be developed after COVID-19 mRNA vaccination.

Anti-glomerular basement membrane (anti-GBM) antibody disease is a rapidly progressive glomerulonephritis characterized by (i) positivity to anti-GBM in serum reacting with a specific antigen present in type IV collagen at both the glomerular and alveolar levels (ii) presence of crescent on light microscopy and positivity to linear deposits of IgG and C3 on immunofluorescence. In the classic variant, the clinic is that of a nephro-pneumological syndrome but there are variants. Rarely, the glomerular damage is pauci-immune. We describe a case of a variant in which there is anti-MBG positivity in serum but negative immunofluorescence and offer a review of the literature and potential treatments.

Diffuse large B-cell lymphoma (DLBCL) with signet ring cell components is extremely rare. Here, we present a case of DLBCL with signet ring cell components involving the breast, which can be easily confused with invasive lobular carcinoma of the breast or metastatic signet ring cell carcinoma of gastrointestinal origin.
A 66-year-old woman presented with a painless mass in her left breast. Enhanced magnetic resonance imaging (MRI) of the breast revealed a 42 × 29 × 28 mm mass in the left breast. Histological examination revealed a diffuse or scattered arrangement of round cells mixed with signet ring-like cells. Immunohistochemically, the neoplastic cells were positive for PAX-5, CD79a, CD20, Bcl-6, and MUM-1 but and negative for cytokeratin, ER, PR, E-cadherin, and P120. The Ki-67 proliferation index was approximately 70%. Fluorescence in situ hybridisation (FISH) demonstrated non-rearrangement of Bcl-2, Bcl-6, and c-MYC genes. Immunohistochemistry and FISH examination confirmed the diagnosis of DLBCL. Subsequently, immunofluorescence showed both IgM and IgG deposits in the signet ring-like lymphocytes. After confirming the diagnosis, the patient received four courses of CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone) chemotherapy in a specialist hospital and achieved partial remission; however, she unfortunately died of secondary pneumocystis pneumonia infection 3 months later.
Malignant lymphoma with signet ring cell morphology is quite uncommon, and this variant can be a diagnostic pitfall. We emphasise that pathologists should consider lymphoma in the differential diagnosis of malignant breast tumours.

Henoch-Schönlein purpura (HSP) is the most common vasculitis in childhood, presenting with purpura, predominantly of the lower extremities and occasionally with renal involvement as well. Although associated with childhood, HSP, although rarely, can also develop in adults as well. Here we present a patient in his sixties, presenting with a myriad of rash units on his lower extremities, including bullous ones, and a constellation of chronic kidney failure. Skin and renal biopsy specimens revealed morphological changes and immune depositions representative of HSP. Despite treatment, the patient\'s kidney failure slowly progressed, and he expired eight months after his presentation due to associated complications. Although rare, the bullous form of HSP can be viewed as a more aggressive form of the disease, as seen by the presentation constellation and rapid progression in our case.

Rare cases of immunoglobulin G (IgG)-dominant immune complex-mediated glomerulonephritis demonstrate immunoglobulin subclass restriction without light chain restriction. Some of these cases may represent proliferative glomerulonephritis with monotypic immunoglobulin deposits (PGNMID) in which monotypic immunoglobulin is obscured by coexisting polytypic immunoglobulin. However, rigorous demonstration of this possibility is lacking to date. Here, we describe a case of IgG3-restricted immune complex-mediated glomerulonephritis without light chain restriction that apparently \"transformed\" into IgG3κ-PGNMID in a subsequent biopsy. We demonstrate, using several ancillary techniques, including use of the newly described antibodies directed against the conformational epitope at the junctions of heavy and light chains (HLC-IF), that the first biopsy likely represents IgG3κ-PGNMID in which monotypic IgG3κ was hidden by polytypic IgM. This case underscores the need to consider PGNMID in a differential diagnosis of IgG-dominant immune complex-mediated glomerulonephritis without light chain restriction and highlights the potential utility of IgG subclass staining and HLC-IF in such cases to detect monotypic immunoglobulin that may be obscured by coexisting IgM and/or IgA deposits.

Diabetes mellitus is one of the foremost diseases in the modern era and diabetic nephropathy contributes to a major percentage of end-stage kidney disease. Although diabetic nephropathy is difficult to revert back, detection of nondiabetic renal disease (NDRD) is important to detect as most of them are treatable. We describe a case of a 62-year-old female with long-standing diabetes mellitus presenting with massive proteinuria and clinical features of nephrotic syndrome. The kidney biopsy showed class III diabetic nephropathy along with focal proliferative glomerulonephritis with crescent formations. The immunofluorescence study showed strong mesangial IgA deposition with the predominance of lambda stain. This confirmed the diagnosis of diabetic nephropathy with superimposed IgA nephropathy. We reviewed eight Indian studies herewith to demonstrate NDRD spectrum in the Indian diabetic scenario.

Pemphigoid vegetans is a rare variant of bullous pemphigoid characterized by vegetative and purulent lesions of the groin, axillae, thighs, hands, eyelids, and perioral regions. The clinical features and histological findings of pemphigus vegetans and immunohistochemical characteristics of bullous pemphigoid are shown. An 86-year-old woman presented with vegetative lesions in the vulva and groin, and blisters on the head, neck, axillae, and thighs. Although clinically suspected as pemphigus vegetans, skin biopsy showed subepidermal clefts with eosinophil infiltration and eosinophilic pustules in the epidermis. Direct immunofluorescence analysis showed linear deposition of immunoglobulin (Ig)G along the basement membrane zone. Indirect immunofluorescence using 1 mol/L NaCl salt-split skin showed linear deposition of IgG on the epidermal side. Chemiluminescent enzyme immunoassay and enzyme-linked immunosorbent assay were positive for BP180 and BP230. Immunoblotting of recombinant protein of the BP180 C-terminal domain showed positive reactivity. Pemphigoid vegetans was diagnosed and treated successfully with oral corticosteroids. This is the first case of pemphigoid vegetans reported to date with detection of autoantibodies against both BP180 C-terminal domain and BP230.

UNASSIGNED: To describe a case series of scleritis associated with IgA vasculitis (IgAV) at a tertiary referral center.
UNASSIGNED: Three men with scleritis associated with IgAV were identified: one with anterior scleritis alone, one with anterior scleritis and peripheral ulcerative keratitis (sclerokeratitis), and one with anterior and posterior scleritis. Visual acuity was preserved except from the patient who developed posterior scleritis. Ocular pain was the main symptom at presentation. All patients had a previous history of palpable purpura, but only one was aware of his underlying IgAV. Laboratory results revealed microhematuria and proteinuria with normal urinary β2 microglobulin levels and negative serum ANCAs. Skin or kidney biopsy demonstrated leukocytoclastic vasculitis or glomerulonephritis with dominant IgA immune deposits.
UNASSIGNED: Although uncommon, IgAV should be included in the differential diagnosis of anterior scleritis alone or associated with peripheral ulcerative keratitis or posterior scleritis, even in systemically asymptomatic patients. Urinalysis should not be underestimated in assessment of scleritis to detect early stages of glomerular disease. Scleritis may be the first manifestation whose study may lead to the diagnosis of IgAV. Multidisciplinary approach is necessary to prevent irreversible organ damage such as renal failure.

BACKGROUND: Pemphigus erythematosus (PE) is a rare autoimmune skin condition with clinical, histopathological, and serological features that show overlap between lupus erythematosus and pemphigus foliaceus. It typically presents with erythematous, scaly plaques and has a female predominance.
METHODS: After Institutional Review Board (IRB) approval, we searched the internal pathology database for \"pemphigus erythematosus\" in the diagnostic line between 1 January 2000 and 30 July 2020. A comprehensive chart review was performed to collect patient demographics, clinical presentation, and treatment course. We performed a review of the literature and clinical, histopathological, and serological features were collected for comparison to our case series.
RESULTS: Five patients in the case series and 87 patients in the literature were diagnosed with PE. Clinical, histopathological, and serological features were consistent with what has been reported in the literature, although our cohort demonstrated a younger age at presentation, along with a higher proportion (80%) of Black patients. Of the 25 patients in the literature whose race was reported, only five patients (20%) were reported to be Black.
CONCLUSIONS: This is the first case series of PE that has shown an increased prevalence among middle-aged Black patients. No specific trend in regards to race was seen in the review of the literature.