Local vs. systemic pulmonary amyloidosis-impact on diagnostics and clinical management

Immunoglobulin-derived light-chain (AL) amyloidosis of lungs and bronchi can appear as a systemic and a local form. While systemic AL amyloidosis may need haemato-oncological care, the localised form can be treated restrained. We re-evaluated 207 specimens of lungs and bronchi sent in for amyloid diagnostics. Amyloid was diagnosed by polarization microscopy using Congo red-stained tissue specimens and classified immunohistochemically. Histoanatomical amyloid distribution patterns were documented as well as additional histological findings. For 118 patients with AL amyloidosis, we retrieved clinical data. CT scan results were available from 59 patients. AL amyloidosis was the most common type (183 cases). AL was found in 141 and of AL in 27 cases. Fifteen cases were AL amyloid not otherwise specified. Twenty cases harboured transthyretin and three serum amyloid A derived amyloid. By correlation of histoanatomy, radiological and clinical data, amyloid was rarely in the initial differential diagnosis. Local AL amyloidosis often presented with a nodular pattern on CT scan and showed a significantly better disease-specific 10-year survival compared with systemic AL amyloidosis (96.0 vs. 51.9%). Localised and systemic pulmonary and bronchial AL amyloidosis are having a completely different prognosis. While CT scan might be indicative, histological and clinical assessment are mandatory to reach a proper diagnosis and guide patient care.