Generalized early inflammatory morphea mimicking interstitial T-cell lymphoma: A diagnostic pitfall.

Early generalized morphea can clinically mimic mycosis fungoides. The microscopic features of early inflammatory morphea may show variable degrees of infiltration and do not have the characteristic dermal collagen sclerosis. We report the case of a 63-year-old female patient who presented with a 2-month history of an asymptomatic skin rash. Physical examination revealed multiple erythematous to dusky patches on the trunk and thighs, resembling the patch stage of mycosis fungoides. Two skin biopsies were performed, both of which showed prominent interstitial lymphoid infiltration in the reticular dermis without dermal sclerosis. Small lymphocyte exocytosis and lining along the dermal-epidermal junction were observed focally in the epidermis. Small clusters of plasma cells and eosinophils were observed in perivascular areas. Although no predominant clonality was found for CD4 and CD8 stains, 50% loss of CD5 antigen and 90% loss of CD7 antigen expression were apparent in immunohistochemical studies. Subsequent blood tests showed a normal blood cell count and positive human T-lymphotropic virus Type 1 antibodies. The overall findings suggested interstitial mycosis fungoides or early adult T-cell lymphoma-leukemia. The patient refused aggressive treatment, and 3 months later, she presented with indurated plaques from the previous rash. A repeat biopsy revealed the typical features of morphea. This report discussed the pitfalls in the clinical and histopathological diagnosis of early generalized inflammatory morphea that both clinicians and pathologists should consider.

A retrospective study on the direct immunofluorescence findings in pigmented purpuric dermatosis.

BACKGROUND: Pigmented purpuric dermatosis (PPD) is characterized by grouped petechiae, purpuric macules, and pigmentation in the bilateral lower extremities. It runs a chronic and relapsing course. Pathophysiology is poorly understood, but it has been proposed to be an immune-complex disease or capillaritis. This study aimed to determine the incidence and patterns of positive direct immunofluorescence (DIF) findings in patients with clinically and histopathologically confirmed PPD. The association between DIF deposition type and clinical profile was also analyzed. METHODS: Patients with a clinical and histopathologic PPD diagnosis who had undergone DIF studies at a tertiary medical center with attached dermatopathology and immunofluorescence diagnostic centers between January 2002 and December 2021 were included in this study. Data on age, sex, disease duration, comorbidities, and drug intake were collected from medical records. RESULTS: There were 65 patients who satisfied the inclusion criteria. Among them, 58 (89%) had at least one positive finding and 53 (82%) were vascular deposition of immunoglobulin (Ig), complement, or fibrinogen. The most common vascular deposition was fibrinogen (71%) followed by C3 (62%), IgM (18%), IgA (6%), and IgG (3%). Fibrinogen deposition was associated with hypertension (p < 0.03). There was no association between vascular DIF deposition of IgG, IgA, and C3, with age, sex, comorbidities, disease duration, and drug history. CONCLUSION: The most common DIF findings in PPD were vascular deposition of fibrinogen and C3, with or without Ig presence. DIF findings supported a vascular origin in PPD but not an immune complex-mediated disease. Hypertension was associated with fibrinogen deposition and may play a role in its pathophysiology.

Should antituberculosis treatment be prescribed in erythema induratum? A case-control and incidence correlation study in Taiwan, 2001-2020.

BACKGROUND: Erythema induratum (EI) is a tuberculid associated with Mycobacterium tuberculosis infection. Using polymerase chain reaction (PCR), M. tuberculosis has been identified in Taiwan with a high percentage of EI. However, this pathogen is now rarely detected in Taiwan. OBJECTIVES: To explore the association between EI, the annual incidence of tuberculosis (TB) in Taiwan and treatment outcomes over the last two decades. METHODS: Patients diagnosed with EI between 2001 and 2020 were enrolled based on histopathology, tissue culture and positive M. tuberculosis PCR tests. Other cases of panniculitis with positive M. tuberculosis PCR results were used as controls. The clinical information of participants was obtained. The results were correlated with the annual incidence of TB and compared between groups. RESULTS: Fifty-five biopsy specimens from patients with EI met the inclusion criteria; three (5%) had positive M. tuberculosis PCR results. One patient diagnosed with erythema nodosum in the control group had a positive M. tuberculosis PCR (n = 1/27; 4%). There was no significant relationship between M. tuberculosis and EI (odds ratio 1.5, 95% confidence interval -0.964 to 3.964). The correlation between the incidence of M. tuberculosis and the number of EI cases was not statistically significant (r = -0.185, P = 0.45). Only four patients received anti-TB treatment; they all showed clinical improvement without recurrence. One patient with M. tuberculosis PCR-positive EI was not treated with anti-TB therapy; however, the skin lesion improved after 3 months. No other patients in the EI group were diagnosed with M. tuberculosis infection over a follow-up period of 508 person-years. CONCLUSIONS: Most cases of EI in Taiwan are nodular vasculitis and not tuberculid, owing to well-controlled TB. This condition can be alleviated without anti-TB treatment.