Inflammatory leg nodules: A clinical and investigational study.

BACKGROUND: Inflammatory leg nodules are a diagnostically challenging group of dermatoses with limited tools for diagnosis. Considerable overlapping patterns exist despite their distinct clinical and histological features. We attempted to understand if undertaking investigations and studying the clinical course and treatment response can help in differentiating these dermatoses. METHODS: Forty-three patients presenting with inflammatory leg nodules underwent a series of investigations apart from histopathology. The patients were treated as per the final histological diagnosis and observed for response to treatment and followed up to evaluate the clinical course. RESULTS: There was considerable overlap in the investigations done among various dermatoses. These included elevated erythrocyte sedimentation rate (ESR), Mantoux test and antistreptolysin- O (ASLO) titres in the majority of patients while a few had abnormal findings on chest X-ray, CT scan of the chest and doppler ultrasonography of the legs. About 86% of patients with erythema nodosum, 50% with erythema induratum, 57% with cutaneous medium vessel vasculitis and 93% with unclassified panniculitis responded to non-steroidal non-inflammatory drugs (NSAIDs) alone or had spontaneously resolved with only post-inflammatory hyperpigmentation. Other patients required specific treatment with immunosuppressive or immunomodulatory agents. CONCLUSIONS: There is considerable overlap in dermatoses manifesting as inflammatory leg nodules on investigations, treatment received and response to treatment. To categorize them better into distinct entities, this group of dermatoses may require long-term follow-up of the clinical course and response to treatment, repeated investigations especially histopathology during different phases of evolution and progression of disease.

A study of the clinico-histopathological features of erythematous tender nodules predominantly involving the extremities.

BACKGROUND: Erythematous tender nodules predominantly involving extremities are frequently encountered in dermatology and rheumatology practice. They are diagnosed based on distinct clinical and histopathological features. However, in clinical situations, considerable overlap is observed that poses a diagnostic challenge. We undertook a study on clinico-histological patterns of inflammatory nodules over extremities. METHODS: After detailed history and examination, a preliminary clinical diagnosis was made in 43 cases, followed by skin biopsy from representative nodules. Histological diagnosis made was correlated with clinical features. RESULTS: Of 43 cases, a single clinical diagnosis was made in 25 (58.5%) cases while in the remaining cases more than one diagnosis was considered. On correlating with the histopathological diagnosis, concordance was observed in 51% cases while the remaining showed either histological discordance with clinical diagnosis (14% cases) or were kept in the undecided category (35% cases). CONCLUSION: Considerable clinico-histological overlap was observed in inflammatory nodules over extremities. Histopathology alone was not helpful in differentiating one entity from another at all times since variable histo-pathological patterns were seen.

Parthenium dermatitis.

Allergic contact dermatitis (ACD) to Parthenium hysterophorus is the most common cause of plant dermatitis in India. Parthenium dermatitis is caused by dry powder of leaves and flowers and hair-like structures (trichomes). Sesquiterpene lactones (SQLs) are the most important allergens responsible for ACD to parthenium. The different patterns include classical airborne contact dermatitis, chronic actinic dermatitis (CAD), exfoliative and widespread dermatitis. There is a definite trend towards a change from an airborne pattern to a CAD pattern in the natural history of parthenium dermatitis. In CAD, there is a reported increased sensitivity to UVB, UVA and even visible light. However, SQLs including parthenin, the major allergen in the Parthenium hysterophorus, has neither documented photoallergic nor phototoxic properties. Recently, the high photoreactivity of α-methylene-γ-butyrolactone ring toward thymidine and resulting photoadducts has been proposed as an explanation of the progressive evolution of allergic contact dermatitis toward chronic actinic dermatitis. However, more data is required to reach a conclusion on the mechanism of photosensitivity in parthenium dermatitis. Sunlight, especially UV radiation, may have a role in increasing the germination capacity and the amount of allergens in the Compositae family, especially in parthenium plants under appropriate conditions like summer and spring, which may contribute to high prevalence of parthenium dermatitis especially in northern India.