Familial koilonychia.

Sir,

Koilonychia is defined as spooning of finger nails. Acquired Koilonychia is most commonly associated with iron deficiency anemia. Idiopathic and familial types, which are not associated with iron deficiency anemia, are also described. We report the case of a family of 11 members belonging to four generations with Koilonychia.

A 54-year-old man was admitted in the Dermatology ward with irritant contact dermatitis. On examination, all finger nails and six toe nails were either flat or spoon shaped [Figure 1]. On enquiry, he revealed that this was congenital, non progressive and many others in his family also had similar nails from early childhood. Teeth were normal except for dental caries. The family tree is shown in Figure 2.

Figure 1

Finger nails of the patient showing Koilonychias

Figure 2

Family tree showing relatives of the patient with Koilonychias

Hemogram and peripheral smear of the patient were normal. Blood Hemoglobin was 11g %. Serum iron, ferritin and total iron binding capacity were within normal limits. Iron deficiency anemia was thus ruled out. KOH smear and culture from nails did not demonstrate fungus. His sister and daughter were examined and were found to have similar nails [Figure 3]. Their hemogram was normal. Based on the family history and due to lack of evidence of iron deficiency anemia, a diagnosis of familial Koilonychia (FK) was made.

Figure 3

Finger nails of the daughter showing Koilonychias

FK, also known as hereditary or congenital koilonychias, is a rare genetic disease[1] with autosomal dominant type of inheritance with high degree of penetrance.[2-4] It is not associated with ectodermal, systemic or orthopedic defects unlike many other congenital nail diseases.[5] There are three views regarding the pathogenesis of FK. The first that it is due to structural stress incorporated during the keratinisation process of nail formation. The second view is that it is due to a lesser angulation of distal part of nail matrix compared to proximal, altering the direction of nail growth.[5] The third view is that the changes are the result of anoxia and atrophy of distal nail matrix.[6] FK may affect only a few nails[3] or most of the nails.[1] FK must be differentiated from iron deficiency anemia, which is a common disease in our population.

Four generations of a family were affected in our series. In the only previous report from India, only two generations were affected.[5] Besides, this family clearly demonstrates the autosomal dominant mode of transmission of FK. Our case also demonstrates the importance of a carefully taken history with emphasis on family history while evaluating a case of Koilonychia.