Differential Diagnosis

The patient's presentation suggests a complex interplay of her liver disease, alcohol use disorder, and potential nutritional deficiencies. Here's a breakdown of the differential diagnosis:

• Single most likely diagnosis:

  • Alcoholic Neuropathy with Vitamin B12 Deficiency: The patient's long history of alcohol use, symptoms of neuropathy (lack of sensation to touch, pain, temperature, and vibration in both feet and hands), and potential for malabsorption due to liver disease and alcohol use disorder point towards this diagnosis. The increased MCV (mean corpuscular volume) and normal reticulocytes also support a diagnosis related to vitamin B12 deficiency, which is common in alcoholics due to poor diet and malabsorption.

• Other Likely diagnoses:

  • Liver Disease-related Neuropathy: The patient's liver cirrhosis could contribute to neuropathy, either directly or through associated conditions like vitamin deficiencies.
  • Diabetic Neuropathy: Given her type 2 diabetes mellitus, diabetic neuropathy is a consideration, though the presence of other symptoms and lab findings might make it less likely as the sole cause.
  • Wernicke-Korsakoff Syndrome: Although less likely given the description, this condition, associated with thiamine deficiency in alcoholics, could explain some cognitive and neurological findings.

• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):

  • Subacute Combined Degeneration (Vitamin B12 Deficiency): While the patient's symptoms could be attributed to alcoholic neuropathy, the possibility of subacute combined degeneration due to vitamin B12 deficiency is critical to consider and treat promptly to prevent irreversible neurological damage.
  • Thiamine Deficiency: Given the patient's alcohol use disorder, ensuring thiamine levels are adequate is crucial to prevent Wernicke-Korsakoff syndrome, which can be fatal if not treated.

• Rare diagnoses:

  • Porphyria: The hyperpigmented patches could suggest a porphyria cutanea tarda, a condition associated with liver disease and can cause neurological symptoms, though it's less common.
  • Copper Deficiency: Though rare, copper deficiency can cause neurological symptoms and could be considered in the differential, especially if other causes are ruled out.

The lab values that would most likely support the single most likely diagnosis (Alcoholic Neuropathy with Vitamin B12 Deficiency) are:

• MCV increased (indicating macrocytic anemia, common in vitamin B12 deficiency)
• Reticulocytes normal (as the bone marrow's response to anemia might not be significantly affected in a chronic setting like vitamin B12 deficiency)
• Serum homocysteine increased (elevated in vitamin B12 deficiency)
• Serum methylmalonate increased (specifically elevated in vitamin B12 deficiency, distinguishing it from folate deficiency)

Thus, the correct answer reflecting these lab values is B. MCV increased, reticulocytes normal, serum homocysteine increased, and serum methylmalonate increased.