Granulocytic Sarcoma of Parotid Gland in a 4-Year-Old Child with Subleukemic AML: A Diagnostic Challenge!

A 4-year-old male child presented to our outpatient department with large swelling in the parotid region. Routine investigations were all within normal limits, and evaluation of complete blood count was normal except for anaemia. Excisional biopsy as a therapeutic diagnosis was done. Microscopic examination showed monomorphic population of discohesive, hyperchromatic small round cells having high N？:？C ratio, coarse chromatin, conspicuous nucleoli, and sometimes angulated nuclei lying in sheets. Immunohistochemistry was done to rule out possible differential diagnosis. Fine needle aspiration from the swelling showed predominant population of blast cells. Myeloperoxidase and PBO were strongly positive, and diagnosis of granulocytic sarcoma was confirmed. 1. Introduction: Granulocytic sarcoma (GS) also earlier referred to as chloroma or myeloblastoma is an extra medullary tumour composed of granulocytic precursor cells. The term granulocytic sarcoma was coined by Rappaport in 1966 [1]. More recently, the term extramedullary myeloid tumour has evolved. Granulocytic sarcoma occurs in various settings [2] as follows:(i)in association with acute myeloid leukaemia,(ii)in nonleukemic patients with normal peripheral blood and bone marrow findings, but who in due course of time develop acute myeloid leukaemia,(iii)in myelodysplastic syndrome (MDS) with leukemic transformation,(iv)in association with myeloproliferative disorders, where it heralds the onset of blastic transformation. 2. Case Report A four-year-old febrile healthy male child presented with a lump in the right parotid region. On examination, the swelling was about ？cm in size, nontender, irregular, and firm to hard in consistency with obvious proptosis. Swelling extended superiorly up to zygomatic region, inferiorly up to mandible, anteriorly up to maxillary region, and posteriorly up to retromandibular space. Radiological examination showed a large solid ill-defined lesion along the ramus of the mandible extending into masseteric space and until skull base of the right side. Involvement of nasopharynx, posterior ethmoid, and sphenoid sinus with sinus wall remodelling was suggestive of neoplastic mass (Figure 1). Clinical differential diagnosis of rhabdomyosarcoma, lymphoma, and primitive neuroectodermal tumour was suggested. Routine investigations were all within normal limits, and evaluation of complete blood count was normal except for anaemia. On microscopic examination of the processed biopsy, tissue sections showed mainly tumour tissue infiltrating into normal parotid gland (Figure 2). Tumour