Which of the following types of crystals would suppo the likely diagnosis of pseudogout?

Positively-birefringent rhomboidal crystals are classically found in cases of pseudogout. Pseudogout, or calcium pyrophosphate dihydrate (CPPD) disease, tends to affect older individuals, tends to affect the knee, wrist, shoulder, ankle, elbow, and hands, and may develop more insidiously. Neveheless, the similarities between gout and pseudogout require aspiration of the joint for diagnosis. Negatively-birefringent needle-shaped crystals are diagnostic for gout. The other choices are not diagnostic or commonly occurring combinations. Also Know: Pseudogout (also called calcium pyrophosphate dihydrate (CPPD) deposition disease) is most often seen in persons age 60 or older, is characterized by acute, recurrent and rarely chronic ahritis involving large joints (most commonly the knees and the wrists and is almost always accompanied by chondrocalcinosis of the affected joints. Identification of calcium pyrophosphate crystals in joint aspirates is diagnostic of pseudogout. With light microscopy, the rhomboid-shaped crystals differ from the needle-shaped gout crystals. Ref: Hellmann D.B., Imboden Jr. J.B. (2013). Chapter 20. Musculoskeletal & Immunologic Disorders. In M.A. Papadakis, S.J. McPhee, M.W. Rabow (Eds),CURRENT Medical Diagnosis & Treatment 2013.