A 30-year-old non-diabetic, non-hypertensive man developed pain in left side of the chest, pleuritic in nature and localized to left lateral aspect not associated with breathlessness and cough. Subsequently, he developed fever not associated with chills and rigor and swelling on the left lateral lower aspect of the chest, which was painful and gradually increasing. X-ray and CT Scan revealed a lytic leision in the anterior end of left sixth rib with associated subcutaneous soft tissue swelling and enlarged mediatsinal lymphnodes. The patient was tested for HIV antigen and was negative. On the left lower aspect of chest, the patient showed a tender swelling which measured 6 x 5 cms. His haemoglobin and total leucocyte count were normal. Patient's CD4 count was normal and Mantoux test was positive, but Quantiferon gold was negative. Computed Tomography (CT) of head was also done, which was normal. Fine needle aspiration cytology (FNAC) was performed outside and suggestive of cryptoccocal infection. The patient was taken for surgery and 6th rib excision was done.
Histopatholoical examination showed fragments of partly necrotic bone and diffuse chronic inflammatory cell infiltrate including many giant cells, histiocytes, lymphocytes and plasma cells [Figure 1]. The inflammation extended into the subcutaneous soft tissue forming microabcessess. Numerous encapsulated yeast forms, a few showing budding were present within the giant cells [Figure 2] and extracellulary within florid granulomatous inflammation [Figure 2].
A Gomori methenamine silver stain and mucicarmine stain highlighted yeast formed with narrow based budding [Figures 3 and 4]. A final diagnosis of cryptococcal osteomyelitis was given. Culture done for tuberculosis and sputum sent for acid fast bacilli were negative. The patient was started on antifungal treatment and was doing well in his last follow-up.