Changing the way we diagnose tuberculids with interferon gamma release assays.

Diagnosing tuberculids traditionally requires clinicopathological correlation together with positive tuberculin skin tests (TST) or demonstration of Mycobacterium tuberculosis (MTB) DNA by polymerase chain reaction (PCR). Interferon gamma release assays (IGRA) are new laboratory tests approved for the diagnosis of MTB infection. We describe three patients with tuberculids who had no other clinical feature of tuberculosis (TB) infection and negative PCR of skin biopsies. Their diagnoses were aided by positive IGRA.

Extensive hyperpigmented plaques in a chinese singaporean woman: a case of cutaneous plasmacytosis.

Cutaneous plasmacytosis is a rare disease entity presenting with multiple extensive red-brown plaques, histopathology showing marked hyperplasia of mature polyclonal plasma cells, and polyclonal hypergammaglobulinemia on serum protein electrophoresis, in the absence of an underlying secondary cause. We report in this article the first case of cutaneous plasmacytosis from Singapore. A 33-year-old Chinese woman presented with mildly pruritic reddish brown papules and plaques over her trunk and arms for 2 years. Physical examination, laboratory investigations, and radiographic examination were negative for systemic involvement and lymphadenopathy. Serum immunoelectrophoresis showed polyclonal hypergammaglobulinemia with immunoglobulin G and immunoglobulin A. Two sets of skin biopsies performed 2 years apart essentially showed similar histopathological findings of a superficial and deep perivascular infiltrate with numerous mature plasma cells and small typical lymphocytes. There were lymphoid follicles with well-formed germinal centers and mantle zones, surrounded by mature lymphocytes. No light chain restriction was present on immunohistochemistry, and polymerase chain reaction for heavy chain gene rearrangement was negative for monoclonality. Despite potent topical corticosteroids and 8 months of phototherapy with narrow band ultraviolet light, there was no improvement. Intralesional triamcinolone injections to a few lesions afforded temporary relief of itch and flattening of lesions.

Follicular mycosis fungoides mimicking a cutaneous B-cell lymphoproliferative disorder.

Follicular mycosis fungoides (MF) is an uncommon histological variant of MF characterized by infiltrates of atypical lymphocytes around and within the epithelium of the hair follicles (folliculotropism). Here we report a patient with rapidly progressive follicular MF on the face, associated with concurrent typical MF lesions elsewhere. The histology was unusual, as apart from dense lymphoid infiltrates showing folliculotropism and epidermotropism, there was a prominent B-cell component with germinal centres, leading to an initial diagnosis of cutaneous B-cell lymphoma. The final diagnosis of follicular MF was established on demonstration of clonal T-cell receptor gene arrangements and lack of clonality for heavy chain gene rearrangements. This case illustrates a variant of MF that has a more rapid progression than the otherwise indolent course of classical MF over many years, and the diagnostic pitfalls, whereby the histology can mimic a B-cell proliferative disorder.

Solitary fibrous tumour in the deep soft tissue of the neck in a Chinese man.

Originally described in the pleura, solitary fibrous tumour (SFT) is now reported in a variety of extrapleural sites. However, description of SFT in the deep soft tissue of the neck is very rare. In this report, we document the neoplasm, deep to the right platsyma muscle but superficial to the deep fascia just above the clavicle, in an otherwise well 50-year-old Chinese man. Histological examination of the excised specimen disclosed spindle-shaped cells disposed in short fascicles as well as randomly in association with areas of varying cellularity, keloidal hyalinisation of the stroma and haemangiopericytoma-like vessels. The tumour cells were CD34-, bcl-2- and CD99-positive. Since histological features may not accurately predict the biological behaviour of this tumour, careful long-term follow-up is advocated.