<prompt> Max Joseph space is a histopathological feature of?PsoriasisLichen planusPityriasis roseaParapsoriasis  <response>: Ans. B Lichen planus. Ref. Rooks dermatology7th 42.3Histological features of Lichen planus LP The earliest finding is an increase in epidermal Langerhans cells, associated with a superficial perivascular infiltrate of lymphocytes and histiocytes, impinging on the dermal-epidermal junction DEJ. A focal increase in thickness of the granular layer and infiltrate corresponds to the Wickhams striae.0 Degenerating basal epidermal cells are transformed into colloid bodies appear singly or in clumps.0 The rete ridges may appear flattened or effaced saw-tooth appearance. Focal separation from the dermis may lead Max Joseph spaces.Q In active LP, band-like infiltrate of lymphocytes and histiocytes, rarely with plasma cells, obliterates DEJ. Epidermal melanocytes are absent or considerably decreased in number, while pigmentary incontinence with dermal melanophages is characteristic.Histopathology of psoriasis Hyperkeratosis Parakeratosis involves startum corneum Thinning absence of stratum granulosum Munromicro abscess in parakeratotic startum corneum Spongiform pustules of kagoj in St. malpighi Dilated and tortous papillary capillaries with thinning of supra paillary epidermal plates. 