Primary Cutaneous Diffuse Large B-Cell Lymphoma of the Upper Limb: A Fascinating Entity
A male patient, aged 82, retired accountant by profession, sought medical assistance in October 2011, complaining of a nodular skin swelling on the upper medial arm []. The patient initially reported the appearance of small swellings in the right arm, which slowly progressed to a nodular growth over a period of many months. He denied any history of developing a rash, fever, night sweats, or weight loss. Clinical examination revealed a nodular swelling, reddish in appearance, mobile, non-tender, firm in consistency, and measuring 5 cm × 3 cm in size. Neither any axillary or generalized lymphadenopathy nor hepatosplenomegaly were detected. His systemic examination did not reveal any abnormality. Investigations revealed him to have a normal hematological profile, i.e., hemoglobin (13.9 g/dL), platelet count (2,20,000/mm3), ESR –11 mm fall at the end of 1st h, TLC (8,200/mm3), DLC P (64) L (32) M (01) E (03), and Prothrombin time 15/14 s. His biochemical parameters did not show any abnormality, i.e., blood urea – 56 mg/dL, serum creatinine-1.2 mg/dL, normal blood sugar profile, serum sodium – 139 mEq/L, potassium – 4 mEq/L, total bilirubin – 0.6 mg/dL, serum total proteins – 6.5 mg/dL, albumin – 4.3 mg/dL, globulin – 2.2 mg/dL, serum AST – 22 IU/L, and serum ALT – 16 IU/dL. He was found to be non-reactive for HBsAg, HCV, and HIV antigens. Urine routine and microscopic examination was unremarkable. He underwent a wide local excision of the lesion on 25 October 2011 at a civil hospital with a clinical diagnosis of an abscess. The histopathological review done at our center showed an unencapsulated tumor in the superficial dermis, with distortions of the natural architecture of the skin and destruction of the cutaneous appendages. The tumor was composed of large cells arranged in sheets. These cells were round to oval, had scant cytoplasm, pleomorphic vesicular nuclei, and prominent nucleoli []. Dispersed among these large cells were few small lymphoid cells. An initial opinion of poorly differentiated round cell tumor was offered. Immunohistochemistry (IHC) was carried out using monoclonal antibodies against CD45, pancytokeratin (CK), human melanoma black (HMB) 45, Carcinoembryonic antigen (CEA) [Figure and ], and S100 protein. The IHC was positive for CD45 [] and negative for CK, HMB 45, CEA, and S100, thereby proving the lymphoid origin of the tumor cells. The subtyping of the tumor by IHC showed the predominant large cells were positive for CD 20 [] with the intervening small cells staining for CD 3, thereby delineating the B-cell lineage of tumor cells. The tumor cells revealed Bcl2 [], Bcl6 positivity, and a high (Mindbomb homolog) MIB-1 labeling index []. Co-relating histomorphology and immunohistochemistry, a final diagnosis of Primary cutaneous diffuse large B-cell lymphoma – leg type was made.