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Introduction: Scabies is a common parasitic infestation caused by the mite Sarcoptes scabiei. Scabies can mimic other entities clinically, resulting in misdiagnosis. The presence of a mite in the stratum corneum on biopsy specimens is diagnostic of scabies. However, there are instances when mites are not visible, and immunohistochemical (IHC) staining may be misleading. An example is when IHC demonstrates Cluster of Differentiation 1a and S100 positivity. The main differential diagnosis for this finding is Langerhans cell histiocytosis, a group of idiopathic disorders of bone marrow-derived Langerhans cells, with manifestations ranging from isolated to life-threatening multisystem disease. Case Presentation: We present a case of a patient who was diagnosed with Langerhans cell histiocytosis based on histological findings, further review with a repeat reading and deeper sectioning of her biopsy revealed a mite in the stratum corneum, altering the diagnosis, course, and management. She subsequently developed persistent post-scabietic nodules, an underreported entity that may occur following infestation and persist for up to a year. These lesions are self-limiting and do not require repeated courses of treatment. Conclusion: Langerhans cell hyperplasia may be seen in a multitude of entities, including scabies. Familiarity with this phenomenon is crucial to avoid unnecessary invasive investigations, aggressive management and alleviate patients' concerns.
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Neonatal lupus erythematosus (NLE) is a rare autoimmune disorder of newborns and infants, born to usually asymptomatic mothers with lupus erythematosus. Clinical manifestations include variable cutaneous findings, with possible cardiac or hepatic involvement. We present a case of a 3-month-old baby girl with NLE, born to an asymptomatic mother. Her atypical clinical presentation included hypopigmented atrophic scars on the temples. She improved with topical pimecrolimus cream, with almost complete resolution of the facial lesions and improvement in atrophy noted at the 4-month follow-up visit. Cutaneous findings of hypopigmentation and atrophic scarring are less commonly reported. To our knowledge, no similar cases have been published in the Middle East. We aim to share this interesting case, highlight the different clinical presentations of NLE and raise awareness among physicians about this variable phenotype of NLE for timely diagnosis of this uncommon entity.
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Methotrexate-induced accelerated nodulosis (MIAN) is not an uncommon adverse effect associated with the use of the methotrexate in rheumatoid arthritis. Limited case reports describe panniculitis as a pathological finding in this setting. A 31-year-old female with seropositive rheumatoid arthritis on methotrexate therapy presented with a 2-week history of sudden onset of painful infiltrated subcutaneous nodules on both forearms. Based on clinical and histological findings, a diagnosis of methotrexate-induced panniculitis was made. The majority of MIAN case reports that we reviewed showed characteristic pathological findings of classic rheumatoid nodules; few reported panniculitis as a finding. This case illustrates the importance of recognizing this phenomenon as methotrexate-induced panniculitis should be considered in the differential diagnosis of any patient receiving methotrexate presenting with a recent history of accelerated nodulosis. Discontinuation of methotrexate remains controversial.
