ABSTRACT
Background@#Dermatomyositis - a rare autoimmune myositis – is a disease affecting primarily the skin and muscles which has been correlated with an elevated risk of solid tumors - commonly affecting the ovaries, breast, colon and nasopharynx. However, there is a rare association between dermatomyositis and pulmonary large cell neuroendocrine carcinoma such that in a thorough literature review of published material, only two cases have been reported internationally and none locally. Large cell neuroendocrine carcinoma - in itself, is also a rare malignancy representing only 1-3% of all primary lung carcinomas.@*Case Presentation@#This is a case of a 53-year-old Filipino female, hypertensive, diabetic, dyslipidemic, hypothyroid - nonsmoker – who presented with an eight-month history of facial erythema, swelling of bilateral metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints, and erythema over extensor surfaces of the MCP and PIP joints. She had markedly elevated creatine kinase MM and positive anti-nuclear antibody for which she was prescribed prednisone, which she did not comply with. She lost weight and experienced severe abdominal pain. Abdominal imaging subsequently revealed multiple confluent abdominal and thoracic lymphadenopathy with histopathology of large cell neuroendocrine carcinoma (LCNEC). Peculiar to this case however is that despite being a lung carcinoma, the scan showed no pulmonary masses or nodules. Immunohistochemical stains of the lymph node were positive for neuroendocrine markers: pancytokeratin, synaptophysin, TTF-1 and negative for any mutation in the epidermal growth factor receptor. Her Ki-67, which is used as a prognostic factor and correlates with mitotic count - was 70% and PD-L1 tumor proportion score – a predictor of therapeutic effect - is 5-10%. She was subsequently diagnosed with dermatomyositis and pulmonary LCNEC. She has presently completed her 8th cycle of cisplatin and etoposide and has gained weight. Presently, her musculocutaneous lesions have resolved. However, a repeat PET scan was done still showing multiple confluent paraaortic, aortocaval, pericaval lymph nodes with no significant interval change from the first PET scan. Next generation sequencing had been requested showing DIS3 to be the gene altercation – however, as of this writing, no available therapeutic modalities are available to target this. Patient was nonetheless given Pembrolizumab for 3 cycles and subsequently expired due to complications of pneumonia.@*Conclusion@#Among published data, we herein present the third reported case of dermatomyositis associated with pulmonary large cell neuroendocrine carcinoma worldwide and the first reported case in the Philippines thereby contributing to the present medical literature. This case demonstrates two rare diseases associated with each other and exemplifies the need for an awareness of such disease entities. It demonstrates a rare case of LCNEC peculiarly without any pulmonary masses or nodules. It also illustrates the necessity in evaluating patients with dermatomyositis for their respective risk in terms of malignancy and other immunocompromised states. Lastly, it contributes to the knowledge on therapeutic options that may be given to patients presenting with both disease entities.