SESSION TITLE: Miscellaneous Cases I
SESSION TYPE: Affiliate Case Report Slide
PRESENTED ON: Sunday, October 26, 2014 at 10:45 AM - 12:00 PM
INTRODUCTION: Pulmonary light chain deposition disease (LCDD) usually manifests as diffuse cystic lung disease. LCDD causing pulmonary nodules are exceedingly rare and FDG-PET (fluorodeoxyglucose-Positron emission tomography) uptake of these lung nodules are not clearly defined. We report a unique case of pulmonary LCDD presenting with FDG-PET positive lung nodules.
CASE PRESENTATION: Fifty-nine year old female, never smoker, presented with mild shortness of breath on exertion. Her other medical problem was Sjogren’s syndrome for which she received immunosuppresive therapy in the past. Her CT scan of chest revealed thin walled cystic spaces throughout lung and a 1.8 x 2.2 cm nodule in right lower lobe with irregular margin, spiculation, 16 HU (Hounsfield Unit) enhancements (figure 1). The nodule was FDG-PET avid (SUVmax 4.6). Subsequently, the patient underwent wedge resection of the right lower lobe nodule. Pathology revealed deposits of amorphous eosinophilic material (figure 2), which was negative for congo red and thioflavin stains. Immunohistochemical stains were inconclusive. Mass spectrometry showed kappa light chain without amyloid-associated proteins, consistent with LCCD. Lymphoplasmacytic disorders and monoclonal gammopathy were excluded by flow-cytometry, protein electrophoresis and urinary free light chain estimation.
DISCUSSION: Pulmonary nodules are extremely rare presentations of pulmonary LCDD. Solitary nodules are usually asymptomatic, in contrast to diffuse or multinodular variant. Multi-organ involvement is unusual in pulmonary nodular LCCD variant, as monoclonal light chain synthesis is a localized process. It can be associated lymphoproliferative disorders/plasma cell dyscrasias or Sjogren’s syndrome. Light chain deposits in lung are predominantly ĸ isotype with amorphous globular or granular dense deposits and 80% patients show free light chain in serum or urine, unlike our patient. It has a relatively better outcome compared to other similar diseases. The uniqueness of this case include positive FDG-PET scan, an implausible finding with this condition.
CONCLUSIONS: Light chain deposition in the lung can present as hyper-metabolic FDG-PET positive pulmonary nodules mimicking malignancy. It is essential to perform a tissue diagnosis to distinguish this condition prior to any therapy.
Reference #1: Bhargava P, Rushin JM, Rusnock EJ, Hefter LG, Franks TJ, Sabnis SG, Travis WD. Pulmonary light chain deposition disease: report of five cases and review of the literature. Am J Surg Pathol. 2007;31(2):267 -76.
DISCLOSURE: The following authors have nothing to disclose: Debabrata Bandyopadhyay, Tanmay Panchabhai, Valeria Arrossi, Claudiu Cotta, Samar Farha
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