Lymphoma: This condition often presents with enlarged lymph nodes and can be associated with systemic symptoms such as sensitivity to light and noise due to potential paraneoplastic syndromes or direct effects of the lymphoma on the central nervous system. Memory loss could be related to brain involvement or secondary effects of the disease.

Multiple Sclerosis (MS): MS can cause a wide range of neurological symptoms, including sensitivity to light and noise, and cognitive impairments such as memory loss. Enlarged lymph nodes might not be a primary feature but could be seen in the context of an MS relapse or as part of a differential diagnosis for neurological conditions.
Chronic Fatigue Syndrome (CFS)/Myalgic Encephalomyelitis (ME): Patients with CFS/ME often report sensitivity to light and noise, and cognitive symptoms like memory loss are common. Lymphadenopathy can sometimes be present, especially in the early stages of the illness.
Systemic Lupus Erythematosus (SLE): SLE is a systemic autoimmune disease that can affect multiple organ systems, including the nervous system, causing symptoms like sensitivity to light, memory loss, and can also cause lymphadenopathy.

Neurosyphilis: This condition, caused by the bacterium Treponema pallidum, can present with a wide range of neurological symptoms, including memory loss, and can also cause sensitivity to light and noise. Lymphadenopathy might be seen in the secondary stage of syphilis. Missing this diagnosis could lead to severe neurological damage if not treated promptly.
HIV/AIDS: Early stages of HIV infection can present with lymphadenopathy, neurological symptoms, and increased sensitivity to light and noise. Memory loss can occur due to the direct effect of the virus on the brain or due to opportunistic infections.
Central Nervous System (CNS) Lymphoma: Although rare, CNS lymphoma can cause a variety of neurological symptoms, including memory loss and sensitivity to light and noise. It is crucial not to miss this diagnosis due to its aggressive nature and the need for prompt treatment.

Whipple's Disease: A rare, systemic bacterial infection caused by Tropheryma whipplei, which can affect the central nervous system, causing symptoms like memory loss, and can also lead to lymphadenopathy and sensitivity to light and noise.
Subacute Sclerosing Panencephalitis (SSPE): A rare chronic, progressive encephalitis that affects primarily children and young adults, caused by a persistent infection with the measles virus. It can cause a range of neurological symptoms, including memory loss and sensitivity to light and noise, but lymphadenopathy is not typically a primary feature.