Introduction: Extranodal NK/T cell lymphoma is a rare tumour, typically involving the upper aerodigestive tract. Even rarer is primary extranasal disease involving the skin, testis, soft tissue and gastrointestinal tract. Case Report: We report a case of a 46-year-old Chinese male who presented with six months history of abdominal pain, weight loss and rectal bleeding. Diagnostic colonoscopy revealed multiple aphthous ulcers within the ileo-caecal region and distal transverse colon, separated by normal mucosa, mimicking skip lesions of Crohn’s colitis. Computer topography (CT) scan of the abdomen showed multiple circumferential thickenings involving predominantly the right colon. A clinical diagnosis of colonic Crohn’s disease with possible perforation was made. An extended right hemicolectomy was performed due to uncontrolled rectal bleeding. Histopathology examination of the colon showed infiltration by malignant lymphoid cells associated with necrosis, angiocentricity and angiodestruction. Immunohistochemical studies confirmed T-cell monoclonality, presence of cytotoxic granules and Epstein-Barr virus (EBV) infection. A diagnosis of extranodal NK/T cell lymphoma of the colon was made. Discussion: These findings highlight that colonic NK/T cell lymphoma may clinically mimic other benign inflammatory lesions and should be one of the differential diagnoses in patients presenting with gastrointestinal lesions. The final diagnosis is only possible with appropriate histological and immunohistochemical studies.
gastrointestinal lymphoma

Oncocytic carcinoma of the salivary gland is an uncommon tumour in the head and neck region. Owing to its rarity, identifying the histopathological features of a malignant tumour can be difficult and challenging. We report a case of a 70-year-old man who presented with a left facial weakness for six months in a background history of left parotid swelling over the past 10 years. Clinical examination revealed a 3x3cm left parotid mass and grade 4 facial nerve palsy. Fine needle aspiration of the mass showed scattered cohesive, monolayered sheets of uniform oncocytic cells. Subsequently, a left total parotidectomy and selective neck dissection were performed. Histological examination showed sheets of small oncocytes with minimal nuclear atypia. Evidence of nerve entrapment, capsular invasion and perivascular permeation were identified in focal areas. Thus, a final diagnosis of oncocytic carcinoma was rendered.

Histiocytic proliferation of the skin can be categorised into Langerhan and non-Langerhan types. Benign cephalic histiocytosis (BCH) is a rare cutaneous non-Langerhan histiocytosis typically affecting infants and young children. We report a case of benign cephalic histiocytosis in a boy who, at seven months of age, presented with multiple yellowish papular eruptions on his face. Over the course of 18 months, the lesion spread to his trunk and upper extremities, sparing the mucous membranes, palms and soles. There was no systemic involvement identified. A histopathologic examination of the skin lesion showed diffuse infiltration of histiocytes within the superficial dermis intermingled with scattered eosinophils and small lymphocytes. Immunohistochemical studies showed that the histiocytes were diffusely positive for CD68. Langerhan markers CD1a and S100 were negative. The correct distinction between BCH and other histiocytic proliferations of the skin is important because BCH has a self-limiting clinical course with a tendency of spontaneous remission.