Background Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is an uncommon cutaneous T-cell lymphoma commonly seen in middle-aged females. Lupus panniculitis (LP) is a close differential of SPTCL and the clinical, histological, and immunohistochemical profiles of these two mimics fairly overlap, making differentiation challenging. Aim This study attempts to see if there is any difference in the cellular myelocytomatosis oncogene (c-MYC) expression of both entities. Methods From the electronic archive of the Department of Histopathology, all cases of SPTCL and LP diagnosed between 2015 and 2022 were retrieved. The c-MYC IHC was performed on nine SPTCL biopsies available from seven patients and eleven LP cases. The percentage of c-MYC-positive cells was quantified and compared between the two groups. Results The mean age of patients with SPTCL and LP was 27.7 years (range: 10-50 years) and 35.9 years (range: 18-62 years), respectively. The c-MYC positivity was higher in cases of SPTCL, ranging from 0.5-22% with a mean of 10.6% and a median of 9%. The LP cases had a lower positivity rate with a range of 0-8% with a mean of 1.9% and a median of 1.2% (p value 0.0005). Additionally, c-MYC positivity was more pronounced in areas with fat entrapment, i.e., in atypical lymphocytes rimming individual fat cells with apoptotic debris. Limitation The limitations include small sample size, absence of FISH studies in all cases and non availability of T cell receptor analysis. Conclusion This study highlights the importance of the IHC of c-MYC in diagnosing SPTCL vs. LP. The higher percentage of c-MYC-positive atypical cells in SPTCL suggests that this oncoprotein may have a significant involvement in the pathogenesis of SPTCL.

Skin colour is determined by four biochromes: oxyhaemoglobin (red), reduced haemoglobin (blue), carotenoids (yellow), and, most importantly, the amount and type of melanin produced and its distribution in the skin. Pigmentary disorders comprise hypopigmentary, hyperpigmentary, and non-melanin pigmentary diseases. While the former two are discussed frequently, non-melanin pigmentary conditions are not unusual. Based on the aetiology and colour of pigmentation, these disorders can be categorised into blue-coloured lesions, hypopigmented lesions due to vascular aetiology, yellow-coloured lesions (xanthoderma), green-coloured lesions, pigmentation caused by heavy metals, and the miscellaneous group comprising conditions like chromhidrosis and ochronosis. While a few of these conditions may be confined to the skin, others can give an important clue to an underlying systemic disease. This review attempts to summarise the conditions that present as non-melanin pigmentation. It is imperative to recognise these entities and provide appropriate treatment to the patient.