This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Skin
A male child with cryptorchidism presents with large black scales on body flexures. Skin biopsy showed hyper granulosis & steroid sulfatase deficiency. Probable diagnosis is: 
Select and explain. 
A. Icthysois vulgaris, B. Icthyosis -lamellar, C. X linked icthyosis nigra, D. Nonbullous icthyosiform erythroderma
C: X linked icthyosis nigra
Answer: C: X linked icthyosis nigra 
Explanation: C. i.e X- linked icthyosis nigra Icthyosis nigra is X-linked recessive disease affecting only males and presenting with large, adherent, generalized, brown to black scales encroaching flexures along with cryptorchidismQ. Skin biopsy shows hyperkeratosis with hyper granulosis and steroid sulfatase deficiencyQ.